David Day

AtNDB2 is the main external NADH dehydrogenase in mitochondria and is important for tolerance to environmental stress

Publisher: Oxford University Press (OUP)

Date: 13-08-2019

DOI: 10.1104/PP.19.00877

Iron transport across symbiotic membranes of nitrogen-fixing legumes

Publisher: MDPI AG

Date: 04-01-2021

DOI: 10.3390/IJMS22010432

Abstract: Iron is an essential nutrient for the legume-rhizobia symbiosis and nitrogen-fixing bacteroids within root nodules of legumes have a very high demand for the metal. Within the infected cells of nodules, the bacteroids are surrounded by a plant membrane to form an organelle-like structure called the symbiosome. In this review, we focus on how iron is transported across the symbiosome membrane and accessed by the bacteroids.

Pyruvate and Malate Transport and Oxidation in Corn Mitochondria

Publisher: Oxford University Press (OUP)

Date: 04-1977

DOI: 10.1104/PP.59.4.630

Cell-to-cell transport via the lumen of the endoplasmic reticulum

Publisher: Wiley

Date: 04-04-2011

DOI: 10.1111/J.1365-313X.2011.04545.X

Nutrient transport across symbiotic membranes from legume nodules

Publisher: CSIRO Publishing

Date: 2001

DOI: 10.1071/PP01028

Differential Expression of the Multigene Family Encoding the Soybean Mitochondrial Alternative Oxidase

Publisher: Oxford University Press (OUP)

Date: 06-1997

DOI: 10.1104/PP.114.2.455

Abstract: The alternative oxidase (AOX) of the soybean (Glycine max L.) inner mitochondrial membrane is encoded by a multigene family (Aox) with three known members. Here, the Aox2 and Aox3 primary translation products, deduced from cDNA analysis, were found to be 38.1 and 36.4 kD, respectively. Direct N-terminal sequencing of partially purified AOX from cotyledons demonstrates that the mature proteins are 31.8 and 31.6 kD, respectively, implying that processing occurs upon import of these proteins into the mitochondrion. Sequence comparisons show that the processing of plant AOX proteins occurs at a characteristic site and that the AOX2 and AOX3 proteins are more similar to one another than to other AOX proteins, including soybean AOX1. Transcript analysis using a polymerase chain reaction-based assay in conjunction with immunoblot experiments indicates that soybean Aox genes are differentially expressed in a tissue-dependent manner. Moreover, the relative abundance of both Aox2 transcripts and protein in cotyledons increase upon greening of dark-grown seedlings. These results comprehensively explain the multiple AOX-banding patterns observed on immunoblots of mitochondrial proteins isolated from various soybean tissues by matching protein bands with gene products.

Cyanide-resistant respiration in roots and leaves. Measurements with intact tissues and isolated mitochondria

Publisher: Wiley

Date: 06-1983

DOI: 10.1111/J.1399-3054.1983.TB04159.X

Pyridine nucleotide interactions with isolated plant mitochondria

Publisher: Elsevier BV

Date: 03-1978

DOI: 10.1016/0005-2728(78)90107-X

Abstract: In search of novel genes expressed in metastatic prostate cancer, we subtracted cDNA isolated from benign prostatic hypertrophic tissue from cDNA isolated from a prostate cancer xenograft model that mimics advanced disease. One novel gene that is highly expressed in advanced prostate cancer encodes a 339-amino acid protein with six potential membrane-spanning regions flanked by hydrophilic amino- and carboxyl-terminal domains. This structure suggests a potential function as a channel or transporter protein. This gene, named STEAP for six-transmembrane epithelial antigen of the prostate, is expressed predominantly in human prostate tissue and is up-regulated in multiple cancer cell lines, including prostate, bladder, colon, ovarian, and Ewing sarcoma. Immunohistochemical analysis of clinical specimens demonstrates significant STEAP expression at the cell-cell junctions of the secretory epithelium of prostate and prostate cancer cells. Little to no staining was detected at the plasma membranes of normal, nonprostate human tissues, except for bladder tissue, which expressed low levels of STEAP at the cell membrane. Protein analysis located STEAP at the cell surface of prostate-cancer cell lines. Our results support STEAP as a cell-surface tumor-antigen target for prostate cancer therapy and diagnostic imaging.

Regulation of Nonphosphorylating Electron Transport Pathways in Soybean Cotyledon Mitochondria and Its Implications for Fat Metabolism

Publisher: Oxford University Press (OUP)

Date: 04-1988

DOI: 10.1104/PP.86.4.1199

Tricarboxylic Acid Cycle Activity in Mitochondria from Soybean Nodules and Cotyledons

Publisher: Oxford University Press (OUP)

Date: 1990

DOI: 10.1093/JXB/41.8.961

Ammonia and amino acid transport across symbiotic membranes in nitrogen-fixing legume nodules

Publisher: Springer Science and Business Media LLC

Date: 2001

DOI: 10.1007/PL00000778

SUGAR AND AMINO-ACID-TRANSPORT ACROSS SYMBIOTIC MEMBRANES FROM SOYBEAN NODULES

Publisher: Scientific Societies

Date: 1990

DOI: 10.1094/MPMI-3-334

Characteristics of External NADH Oxidation by Beetroot Mitochondria

Publisher: Oxford University Press (OUP)

Date: 07-1976

DOI: 10.1104/PP.58.1.38

GmVTL1 is an iron transporter on the symbiosome membrane of soybean with an important role in nitrogen fixation

Publisher: Cold Spring Harbor Laboratory

Date: 05-03-2020

DOI: 10.1101/2020.03.03.975805

Abstract: Legumes establish symbiotic relationships with soil bacteria (rhizobia), housed in nodules on plant roots. The plant supplies carbon substrates and other nutrients to the bacteria in exchange for fixed nitrogen. The exchange occurs across a plant-derived symbiosome membrane (SM), which encloses rhizobia to form a symbiosome. Iron supplied by the plant is crucial for the rhizobial enzyme nitrogenase that catalyses N 2 fixation, but the SM iron transporter has not been identified. We use complementation of yeast and plant mutants, real-time PCR, hairy root transformation, microscopy and proteomics to demonstrate the role of soybean GmVTL1 and 2. Both are members of the vacuolar iron transporter family and homologous to Lotus japonicus SEN1 (LjSEN1), previously shown to be essential for N 2 fixation. GmVTL1 expression is enhanced in nodule infected cells and both proteins are localised to the SM. GmVTL1 and 2 transport iron in yeast and GmVTL1 restores N 2 fixation when expressed in the Ljsen1 mutant. Three GmVTL1 amino acid substitutions that reduce iron transport in yeast also block N 2 fixation in Ljsen1 plants. We conclude GmVTL1 is responsible for transport of iron across the SM to bacteroids and plays a crucial role in the N 2 -fixing symbiosis.

Mitochondrial Structure and Function in Plants

Publisher: Springer Netherlands

Date: 2004

DOI: 10.1007/978-1-4020-2400-9_1

EFFECT OF PHOTOSYNTHESIS AND CARBOHYDRATE STATUS ON RESPIRATORY RATES AND THE INVOLVEMENT OF THE ALTERNATIVE PATHWAY IN LEAF RESPIRATION

Publisher: Oxford University Press (OUP)

Date: 07-1983

DOI: 10.1104/PP.72.3.598

Genomic structure and expression of alternative oxidase genes in legumes

Publisher: Wiley

Date: 06-2019

DOI: 10.1111/PCE.13161

Abstract: Mitochondria isolated from chickpea (Cicer arietinum) possess substantial alternative oxidase (AOX) activity, even in non-stressed plants, and one or two AOX protein bands were detected immunologically, depending on the organ. Four different AOX isoforms were identified in the chickpea genome: CaAOX1 and CaAOX2A, B and D. CaAOX2A was the most highly expressed form and was strongly expressed in photosynthetic tissues, whereas CaAOX2D was found in all organs examined. These results are very similar to those of previous studies with soybean and siratro. Searches of available databases showed that this pattern of AOX genes and their expression was common to at least 16 different legume species. The evolution of the legume AOX gene family is discussed, as is the in vivo impact of an inherently high AOX capacity in legumes on growth and responses to environmental stresses.

Preferential oxidation of glycine by the respiratory chain of pea leaf mitochondria

Publisher: Wiley

Date: 11-07-1983

DOI: 10.1016/0014-5793(83)80698-X

Sequencing of a Soybean Alternative Oxidase cDNA Clone

Publisher: Oxford University Press (OUP)

Date: 12-1993

DOI: 10.1104/PP.103.4.1481

MICROAEROBIC RESPIRATION AND OXIDATIVE-PHOSPHORYLATION BY SOYBEAN NODULE MITOCHONDRIA - IMPLICATIONS FOR NITROGEN-FIXATION

Publisher: Wiley

Date: 07-1995

DOI: 10.1111/J.1365-3040.1995.TB00574.X

Metabolite transport across symbiotic membranes of legume nodules

Publisher: Annual Reviews

Date: 06-1997

DOI: 10.1146/ANNUREV.ARPLANT.48.1.493

Abstract: ▪ Abstract Infection of legume roots or stems with soil bacteria of the Rhizobiaceae results in the formation of nodules that become symbiotic nitrogen-fixing organs. Within the infected cells of these nodules, bacteria are enveloped in a membrane of plant origin, called the peribacteroid membrane (PBM), and ide and differentiate to form nitrogen-fixing bacteroids. The organelle-like structure comprised of PBM and bacteroids is termed the symbiosome, and is the basic nitrogen-fixing unit of the nodule. The major exchange of nutrients between the symbiotic partners is reduced carbon from the plant, to fuel nitrogenase activity in the bacteroid, and fixed nitrogen from the bacteroid, which is assimilated in the plant cytoplasm. However, many other metabolites are also exchanged. The metabolic interaction between the plant and the bacteroids is regulated by a series of transporters and channels on the PBM and the bacteroid membrane, and these form the focus of this review.

The effect of calcium on the respiratory responses of corn mitochondria

Publisher: Elsevier BV

Date: 05-1978

DOI: 10.1016/0005-2728(78)90050-6

Abstract: Tightly coupled respiring corn mitochondria (Zea mays L.) respond to calcium addition with a transitory respiratory increase, proton extrusion, and Ca2+ binding. The extent of response is dependent upon the level of endogenous phosphate, and a large sustained respiratory increase can be obtained with addition of phosphate. However, calcium does not act as a permeant cation in that it will not penetrate with acetate. It appears that the transitory respiratory increase must be linked to the uptake of a calcium phosphate complex, but there is no evidence that transport of the complex serves to produce an electrophoretic calcium uniport. It is believed that calcium phosphate transport in corn is a constitutive property, and not produced by membrane damage.

Malate Decarboxylation by Kalanchoë daigremontiana Mitochondria and Its Role in Crassulacean Acid Metabolism

Publisher: Oxford University Press (OUP)

Date: 04-1980

DOI: 10.1104/PP.65.4.675

Cloning, Analysis and Inactivation of the ndhK Gene Encoding a Subunit of NADH Quinone Oxidoreductase from Anabaena PCC 7120

Publisher: Wiley

Date: 08-1996

DOI: 10.1111/J.1432-1033.1996.0173H.X

Abstract: The function of the type-1 pyridine nucleotide dehydrogenase (NDH-1) in the cyanobacterium Anabaena PCC 7120 was investigated. Immunological analysis with antibodies raised against NdhK from Synechocystis PCC 6803, a subunit of NDH-1, showed that NdhK in Anabaena PCC 7120 is only present on the plasma membrane, which confirms the results of previous studies [Howitt, C.A., Smith, G.D. & Day, D. A. (1993) Biochim. Biophys. Acta 114], 313-320]. Southern analysis with probes from the operon encoding ndhC-K-J from Synechocystis PCC 6803 showed that this operon is also conserved in Anabaena PCC 7120. Part of the operon was lified using PCR with degenerate primers designed against two sequences encoding regions of NdhC and NdhJ that are conserved between cyanobacteria and chloroplasts. The nucleotide sequence of ndhK encodes a protein of 245 amino acids with a predicted molecular mass of 27.5 kDa. The coding regions of ndhC and ndhK overlap by 7 bp, as found in the chloroplasts of liverwort, maize, and rice. This is markedly different from the case in Synechocystis PCC 6803 where a 71-bp non-coding, intergenic spacer region lies between ndhC and ndhK. The ndhK clone was interrupted by the insertion of a kanamycin-resistance gene and used to transform Anabaena PCC 7120.20 unsegregated transformants were produced, all of which died during attempts to segregate them. This indicates that under the selection conditions used, ndhK is an essential gene in Anabaena PCC 7120.

A GmAOX2b antisense gene compromises vegetative growth and seed production in soybean

Publisher: Springer Science and Business Media LLC

Date: 04-02-2012

DOI: 10.1007/S00425-012-1601-6

Abstract: The alternative oxidase mediates the cyanide-resistant respiratory pathway in plant mitochondria. In non-thermogenic plants, the role of alternative oxidase in plant growth and development is not well understood. Soybean (Glycine max) lines carrying a GmAOX2b antisense gene had compromised vegetative growth and reproductive performance under typical glasshouse growth conditions. The reduction in vegetative growth was demonstrated by reduction in shoot height, the number of leaves per plant and the green leaf area. Antisense plants also had decreased pod formation and seed to pod ratios, which together led to a reduction in the number and total mass of seed produced. The negative effects of the antisense gene on pod set, seed set, ovule availability and total seed mass were primarily confined to the branches, rather than the main stem. The preferential effect of alternative oxidase suppression in the branches is discussed in relation to the reproductive potential of soybean under stress. Taken together, these results demonstrate that alternative oxidase provides the benefit of sustaining plant vegetative growth and reproductive capacity in soybean.

Soybean Yellow Stripe-like 7 is a symbiosome membrane peptide transporter important for nitrogen fixation

Publisher: Oxford University Press (OUP)

Date: 05-02-2021

DOI: 10.1093/PLPHYS/KIAB044

Abstract: Legumes form a symbiosis with rhizobia that convert atmospheric nitrogen (N2) to ammonia and provide it to the plant in return for a carbon and nutrient supply. Nodules, developed as part of the symbiosis, harbor rhizobia that are enclosed in a plant-derived symbiosome membrane (SM) to form an organelle-like structure called the symbiosome. In mature nodules exchanges between the symbionts occur across the SM. Here we characterize Yellow Stripe-like 7 (GmYSL7), a Yellow stripe-like family member localized on the SM in soybean (Glycine max) nodules. It is expressed specifically in infected cells with expression peaking soon after nitrogenase becomes active. Unlike most YSL family members, GmYSL7 does not transport metals complexed with phytosiderophores. Rather, it transports oligopeptides of between four and 12 amino acids. Silencing GmYSL7 reduces nitrogenase activity and blocks infected cell development so that symbiosomes contain only a single bacteroid. This indicates the substrate of YSL7 is required for proper nodule development, either by promoting symbiosome development directly or by preventing inhibition of development by the plant. RNAseq of nodules where GmYSL7 was silenced suggests that the plant initiates a defense response against rhizobia with genes encoding proteins involved in amino acid export downregulated and some transcripts associated with metal homeostasis altered. These changes may result from the decrease in nitrogen fixation upon GmYSL7 silencing and suggest that the peptide(s) transported by GmYSL7 monitor the functional state of the bacteroids and regulate nodule metabolism and transport processes accordingly. Further work to identify the physiological substrate for GmYSL7 will allow clarification of this role.

Regulation of alternative pathway activity in plant mitochondria: Nonlinear relationship between electron flux and the redox poise of the quinone pool

Publisher: Elsevier BV

Date: 08-1989

DOI: 10.1016/0003-9861(89)90173-2

Abstract: The dependence of respiratory flux via the alternative pathway on the redox poise of the ubiquinone (Q) pool was investigated in soybean cotyledon mitochondria. A marked nonlinear relationship was observed between Q-pool reduction level and O2 uptake via the alternative oxidase. Significant engagement of the alternative pathway was not apparent until Q-pool reduction level reached 35-40% but increased disproportionately on further reduction. Similar results were obtained with electron donation from either Complex 1 or Complex 2. Close agreement was obtained over a range of experimental conditions between the estimated contribution of the alternative pathway to total respiratory flux, as measured with salicylhydroxamic acid, and that predicted from the redox poise of the Q-pool. These results are discussed in terms of existing models of the regulation of respiratory flux via the alternative pathway.

Glycine transport by pea leaf mitochondria

Publisher: Wiley

Date: 07-04-1980

DOI: 10.1016/0014-5793(80)80177-3

Online Oxygen Kinetic Isotope Effects Using Membrane Inlet Mass Spectrometry Can Differentiate between Oxidases for Mechanistic Studies and Calculation of Their Contributions to Oxygen Consumption in

Publisher: American Chemical Society (ACS)

Date: 05-2014

DOI: 10.1021/AC501086N

Abstract: The reduction chemistry of molecular oxygen underpins the energy metabolism of multicellular organisms, liberating free energy needed to catalyze a plethora of enzymatic reactions. Measuring the isotope signatures of (16)O and (18)O during O2 reduction can provide insights into both kinetic and equilibrium isotope effects. However, current methods to measure O2 isotope signatures are time-consuming and disruptive. This paper describes the application of membrane inlet mass spectrometry to determine the oxygen isotope discrimination of a range of O2-consuming reactions, providing a rapid and convenient method for determining these values. A survey of oxygenase and oxidase reactions provides new insights into previously uncharacterized amino acid oxidase enzymes. Liquid and gas phase measurements show the ease of assays using this approach for purified enzymes, biological extracts and intact tissues.

The Effect of Exogenous Nicotinamide Adenine Dinucleotide on the Oxidation of Nicotinamide Adenine Dinucleotide-linked Substrates by Isolated Plant Mitochondria

Publisher: Oxford University Press (OUP)

Date: 09-1974

DOI: 10.1104/PP.54.3.360

Altering the balance between AOX1A and NDB2 expression affects a common set of transcripts in Arabidopsis

Publisher: Frontiers Media SA

Date: 15-11-2022

DOI: 10.3389/FPLS.2022.876843

Abstract: Stress-responsive components of the mitochondrial alternative electron transport pathway have the capacity to improve tolerance of plants to abiotic stress, particularly the alternative oxidase AOX1A but also external NAD(P)H dehydrogenases such as NDB2, in Arabidopsis. NDB2 and AOX1A can cooperate to entirely circumvent the classical electron transport chain in Arabidopsis mitochondria. Overexpression of AOX1A or NDB2 alone can have slightly negative impacts on plant growth under optimal conditions, while simultaneous overexpression of NDB2 and AOX1A can reverse these phenotypic effects. We have taken a global transcriptomic approach to better understand the molecular shifts that occur due to overexpression of AOX1A alone and with concomitant overexpression of NDB2. Of the transcripts that were significantly up- or down- regulated in the AOX1A overexpression line compared to wild type (410 and 408, respectively), the majority (372 and 337, respectively) reverted to wild type levels in the dual overexpression line. Several mechanisms for the AOX1A overexpression phenotype are proposed based on the functional classification of these 709 genes, which can be used to guide future experiments. Only 28 genes were uniquely up- or down-regulated when NDB2 was overexpressed in the AOX1A overexpression line. On the other hand, many unique genes were deregulated in the NDB2 knockout line. Furthermore, several changes in transcript abundance seen in the NDB2 knockout line were consistent with changes in the AOX1A overexpression line. The results suggest that an imbalance in AOX1A:NDB2 protein levels caused by under- or over-expression of either component, triggers a common set of transcriptional responses that may be important in mitochondrial redox regulation. The most significant changes were transcripts associated with photosynthesis, secondary metabolism and oxidative stress responses.

Proteomic Analysis on Symbiotic Differentiation of Mitochondria in Soybean Nodules

Publisher: Oxford University Press (OUP)

Date: 15-03-2004

DOI: 10.1093/PCP/PCH035

Abstract: Symbiotic interactions between legume plants and rhizobia induce specific metabolisms and intracellular organelles in nodules. For surveying symbiotic differentiation of a key organelle, mitochondria, protein constituents of soybean nodule and root mitochondria were compared after two-dimensional (2-D) electrophoresis, and the proteins were characterized in combination with matrix-assisted desorption/ionization time-of-flight mass spectrometry, electrospray ionization mass spectrometry and N-terminal amino acid sequencing. Of the proteins that were detected only in nodule mitochondria, phosphoserine aminotransferase, flavanone 3-hydroxylase, coproporphyrinogen III oxidase, one ribonucleoprotein and three unknown proteins were identified. Seven up-regulated, eight down-regulated and two strongly suppressed protein spots in nodule mitochondria were also assigned protein identities. The physiological roles of these differential expressions were discussed in relation to nodule-specific metabolisms in soybean nodules.

A channel-like transporter for NH4+ on the symbiotic interface of N2-fixing plants

Publisher: Springer Science and Business Media LLC

Date: 12-1995

DOI: 10.1038/378629A0

THE REGULATION OF RESPIRATION IN THE DARK IN WHEAT LEAF SLICES

Publisher: Elsevier BV

Date: 12-1983

DOI: 10.1016/0304-4211(83)90037-8

Matrix NADH dehydrogenases of plant mitochondria and sites of quinone reduction by complex I

Publisher: Wiley

Date: 09-1992

DOI: 10.1111/J.1432-1033.1992.TB17211.X

Abstract: In order to distinguish the pathways involved in the oxidation of matrix NADH in plant mitochondria, the oxidation of NADH and nicotinamide hypoxanthine dinucleotide (reduced form) was investigated in submitochondrial particles prepared from beetroot (Beta vulgaris L. cv. Derwent Globe) and soybeans (Glycine max L. cv. Bragg). Nicotinamide-hypoxanthine-dinucleotide(reduced form)-oxidase activity was more strongly inhibited by rotenone than the NADH-oxidase activity but both of the rotenone-inhibited activities could be stimulated by adding ubiquinone-1. The corresponding ubiquinone-1-reductase activities were inhibited by rotenone (to 69%) and further inhibited by N,N'-dicyclohexylcarbodiimide (to 79%), whilst the K3Fe(CN)6-reductase activities were not sensitive to either rotenone or N,N'-dicyclohexylcarbodiimide. Immunological analysis of mitochondrial proteins using an antiserum raised against purified beetroot complex I indicated very few differences between soybean and fresh and aged beetroot mitochondria, despite their varying sensitivities to rotenone. We confirm that there are two dehydrogenases capable of oxidising internal NADH and that only one of these, namely complex I, is inhibited by rotenone. Further, we conclude that complex I has two potential sites of quinone reduction, both sensitive to N,N'-dicyclohexycarbodiimide inhibition but only one of which is sensitive to rotenone inhibition.

Cyanide-insensitive oxygen uptake and pyridine nucleotide dehydrogenases in the cyanobacterium Anabaena PCC 7120

Publisher: Elsevier BV

Date: 03-1993

DOI: 10.1016/0005-2728(93)90059-O

GROWTH COMPARISONS OF A SUPERNODULATING SOYBEAN (GLYCINE-MAX) MUTANT AND ITS WILD-TYPE PARENT

Publisher: Wiley

Date: 11-1986

DOI: 10.1111/J.1399-3054.1986.TB03368.X

Adenylate control of respiration in plants: the contribution of rotenone‐insensitive electron transport to ADP‐limited oxygen consumption by soybean mitochondria

Publisher: Wiley

Date: 1990

DOI: 10.1111/J.1399-3054.1990.TB08722.X

Mitochondrial permeability transition induced by dinuclear gold(I)-carbene complexes: potential new antimitochondrial antitumour agents

Publisher: Elsevier BV

Date: 10-2004

DOI: 10.1016/J.JINORGBIO.2004.05.011

Nitric oxide inhibits the cytochrome oxidase but not the alternative oxidase of plant mitochondria

Publisher: Wiley

Date: 02-12-1996

DOI: 10.1016/S0014-5793(96)01230-6

Abstract: Oxygen consumption via the cytochrome pathway in isolated soybean (Glycine max [L.] Merr.) cotyledon mitochondria was inhibited by nitric oxide (NO) while respiration via the cyanide-insensitive alternative oxidase was not significantly affected. Inhibition of cytochrome pathway activity was rapidly reversible upon depletion of the added NO. NO production was also detected in solutions of NaNO2 plus ascorbate and the extent of cytochrome pathway inhibition was dependent on the NO2- concentration. Little inhibition of alternative pathway respiration was observed under similar conditions. The alternative oxidase may play a role in nitric oxide tolerance in higher plants and in organisms such as trypanosomes which contain a plant-like alternative oxidase.

Cytochrome and Alternative Respiratory Pathways Compete for Electrons in the Presence of Pyruvate in Soybean Mitochondria

Publisher: Elsevier BV

Date: 04-1995

DOI: 10.1006/ABBI.1995.1245

Abstract: The partitioning of electrons between the alternative oxidase and the cytochrome pathway of soybean mitochondria has been reassessed in the presence of the alternative oxidase activator pyruvate. In the presence of pyruvate and with succinate as substrate, the alternative oxidase became active at a much lower level of ubiquinone reduction than in the absence of pyruvate. Under state 4 (no ADP present) conditions, activation of the alternative oxidase with pyruvate resulted in an oxidation of b cytochromes, demonstrating switching of electrons away from the cytochrome chain. In the presence of ferricyanide and the cytochrome oxidase inhibitor KCN, cytochrome chain activity could be followed spectrophotometrically and that of the alternative pathway with an oxygen electrode. Under these conditions, the addition of pyruvate erted electron flow from the cytochrome chain to the alternative pathway subsequent inhibition of the alternative oxidase increased electron flow via the cytochrome chain. This indicates that electrons can be switched from one pathway to the other when the cytochrome chain is not saturated and this was confirmed by n-propylgallate titrations (p plots) of mitochondria oxidizing succinate. Decreases in ADP/O ratios and phosphorylation rate upon addition of pyruvate indicated that the alternative pathway could also contribute to respiration under state 3 conditions. The results indicate that when the alternative oxidase is activated by pyruvate, it can compete for electrons with the cytochrome chain and does not act as an overflow pathway. The significance of these observations for in vivo respiration is discussed.

Effects of water stress on respiration in soybean leaves

Publisher: Oxford University Press (OUP)

Date: 26-08-2005

DOI: 10.1104/PP.105.065565

Abstract: The effect of water stress on respiration and mitochondrial electron transport has been studied in soybean (Glycine max) leaves, using the oxygen-isotope-fractionation technique. Treatments with three levels of water stress were applied by irrigation to replace 100%, 50%, and 0% of daily water use by transpiration. The levels of water stress were characterized in terms of light-saturated stomatal conductance (gs): well irrigated (gs & 0.2 mol H2O m−2 s−1), mildly water stressed (gs between 0.1 and 0.2 mol H2O m−2 s−1), and severely water stressed (gs & 0.1 mol H2O m−2 s−1). Although net photosynthesis decreased by 40% and 70% under mild and severe water stress, respectively, the total respiratory oxygen uptake (Vt) was not significantly different at any water-stress level. However, severe water stress caused a significant shift of electrons from the cytochrome to the alternative pathway. The electron partitioning through the alternative pathway increased from 10% to 12% under well-watered or mild water-stress conditions to near 40% under severe water stress. Consequently, the calculated rate of mitochondrial ATP synthesis decreased by 32% under severe water stress. Unlike many other stresses, water stress did not affect the levels of mitochondrial alternative oxidase protein. This suggests a biochemical regulation (other than protein synthesis) that causes this mitochondrial electron shift.

An alternative oxidase monoclonal antibody recognises a highly conserved sequence among alternative oxidase subunits

Publisher: Wiley

Date: 19-03-1999

DOI: 10.1016/S0014-5793(99)00259-8

Abstract: The alternative oxidase is found in the inner mitochondrial membranes of plants and some fungi and protists. A monoclonal antibody raised against the alternative oxidase from the aroid lily Sauromatum guttatum has been used extensively to detect the enzyme in these organisms. Using an immunoblotting strategy, the antibody binding site has been localised to the sequence RADEAHHRDVNH within the soybean alternative oxidase 2 protein. Examination of sequence variants showed that A2 and residues C-terminal to H7 are required for recognition by the monoclonal antibody raised against the alternative oxidase. The recognition sequence is highly conserved among all alternative oxidase proteins and is absolutely conserved in 12 of 14 higher plant sequences, suggesting that this antibody will continue to be extremely useful in studying the expression and synthesis of the alternative oxidase.

Energy costs of salinity tolerance in crop plants

Publisher: Wiley

Date: 29-11-2019

DOI: 10.1111/NPH.15555

Development physiology of cluster-root carboxylate synthesis and exudation in harsh hakea. Expression of phosphoenolpyruvate carboxylase and the alternative oxidase

Publisher: Oxford University Press (OUP)

Date: 05-2004

DOI: 10.1104/PP.103.035659

Abstract: Harsh hakea (Hakea prostrata R.Br.) is a member of the Proteaceae family, which is highly represented on the extremely nutrient-impoverished soils in southwest Australia. When phosphorus is limiting, harsh hakea develops proteoid or cluster roots that release carboxylates that mobilize sparingly soluble phosphate in the rhizosphere. To investigate the physiology underlying the synthesis and exudation of carboxylates from cluster roots in Proteaceae, we measured O2 consumption, CO2 release, internal carboxylate concentrations and carboxylate exudation, and the abundance of the enzymes phosphoenolpyruvate carboxylase and alternative oxidase (AOX) over a 3-week time course of cluster-root development. Peak rates of citrate and malate exudation were observed from 12- to 13-d-old cluster roots, preceded by a reduction in cluster-root total protein levels and a reduced rate of O2 consumption. In harsh hakea, phosphoenolpyruvate carboxylase expression was relatively constant in cluster roots, regardless of developmental stage. During cluster-root maturation, however, the expression of AOX protein increased prior to the time when citrate and malate exudation peaked. This increase in AOX protein levels is presumably needed to allow a greater flow of electrons through the mitochondrial electron transport chain in the absence of rapid ATP turnover. Citrate and isocitrate synthesis and accumulation contributed in a major way to the subsequent burst of citrate and malate exudation. Phosphorus accumulated by harsh hakea cluster roots was remobilized during senescence as part of their efficient P cycling strategy for growth on nutrient impoverished soils.

Mitochondrial protein expression in tomato fruit during on-vine ripening and cold storage

Publisher: CSIRO Publishing

Date: 2002

DOI: 10.1071/PP01245

Abstract: We have investigated the activity and abundance of a number of respiratory chain components in ripening and cold-treated tomato fruits (Lycopersicon esculentum L. Mill cvv. Moneymaker and Sweetie). Expression of the alternative oxidase (AOX) protein increased dramatically in both situations. Levels of the plant uncoupling protein (UCP) initially fell, but increased substantially in the later stages of ripening. In contrast, ATP synthase subunits and the COXII subunit of cytochrome oxidase decreased during ripening and increased slightly in response to cold stress. Other proteins involved in electron transport, tricarboxylic acid cycle function, chaperonin function, and membrane transport were also studied. These showed varying degrees of enhanced and depressed expression patterns. There were modest changes in whole fruit respiratory activities, and electron transport capacity of isolated mitochondria in response to these stimuli. However, respiratory control by ADP in the isolated mitochondria decreased as AOX capacity and abundance increased, indicating that although total respiration rates changed little, flux between the coupled and uncoupled pathways altered. The changes observed in AOX and UCP accumulation in tomato fruit that were vine-ripened were significantly different from post-harvest ripening patterns previously reported. The altered protein profiles are discussed in the context of on- and off-vine ripening and the potentially different roles of uncoupled respiration in each situation.

Siderophore-bound iron in the peribacteroid space of soybean root nodules

Publisher: Springer Science and Business Media LLC

Date: 1996

DOI: 10.1007/BF00011579

Soybean SAT1 ( Symbiotic Ammonium Transporter 1 ) encodes a bHLH transcription factor involved in nodule growth and NH 4 + transport

Publisher: Proceedings of the National Academy of Sciences

Date: 19-03-2014

DOI: 10.1073/PNAS.1312801111

Abstract: The legume/rhizobia symbiosis involves a root-based exchange of bacterial fixed nitrogen for plant-derived photosynthetic carbon. The exchange takes place within the legume root nodule, which is a specialized root tissue that develops in response to plant and bacterial signal exchange. The bacteria reside within plant cells inside the nodule. In this study, we explore the activity of a membrane-bound soybean transcription factor, Glycine max basic–helix-loop–helix membrane 1, which is important for soybean nodule growth and is linked to the activity of a unique class of ammonium channels and to signaling cascades influencing a nodule circadian clock.

Stress-induced co-expression of alternative respiratory chain components in Arabidopsis thaliana

Publisher: Springer Science and Business Media LLC

Date: 05-2005

DOI: 10.1007/S11103-005-5514-7

Abstract: Plant mitochondria contain non-phosphorylating bypasses of the respiratory chain, catalysed by the alternative oxidase (AOX) and alternative NADH dehydrogenases (NDH), as well as uncoupling (UCP) protein. Each of these components either circumvents or short-circuits proton translocation pathways, and each is encoded by a small gene family in Arabidopsis. Whole genome microarray experiments were performed with suspension cell cultures to examine the effects of various 3 h treatments designed to induce abiotic stress. The expression of over 60 genes encoding components of the classical, phosphorylating respiratory chain and tricarboxylic acid cycle remained largely constant when cells were subjected to a broad range of abiotic stresses, but expression of the alternative components responded differentially to the various treatments. In detailed time-course quantitative PCR analysis, specific members of both AOX and NDH gene families displayed coordinated responses to treatments. In particular, the co-expression of AOX1a and NDB2 observed under a number of treatments suggested co-regulation that may be directed by common sequence elements arranged hierarchically in the upstream promoter regions of these genes. A series of treatment sets were identified, representing the response of specific AOX and NDH genes to mitochondrial inhibition, plastid inhibition and abiotic stresses. These treatment sets emphasise the multiplicity of pathways affecting alternative electron transport components in plants.

Expression and kinetics of the mitochondrial alternative oxidase in nitrogen-fixing nodules of soybean roots

Publisher: Wiley

Date: 10-1997

DOI: 10.1046/J.1365-3040.1997.D01-25.X

Salt-induced expression of intracellular vesicle trafficking genes, CaRab-GTP, and their association with Na+ accumulation in leaves of chickpea (Cicer arietinum L.)

Publisher: Springer Science and Business Media LLC

Date: 10-2020

DOI: 10.1186/S12870-020-02331-5

Abstract: Chickpea is an important legume and is moderately tolerant to salinity stress during the growing season. However, the level and mechanisms for salinity tolerance can vary among accessions and cultivars. A large family of CaRab -GTP genes, previously identified in chickpea, is homologous to intracellular vesicle trafficking superfamily genes that play essential roles in response to salinity stress in plants. To determine which of the gene family members are involved in the chickpea salt response, plants from six selected chickpea accessions (Genesis 836, Hattrick, ICC12726, Rupali, Slasher and Yubileiny) were exposed to salinity stress and expression profiles resolved for the major CaRab -GTP gene clades after 5, 9 and 15 days of salt exposure. Gene clade expression profiles (using degenerate primers targeting all members of each clade) were tested for their relationship to salinity tolerance measures, namely plant biomass and Na + accumulation. Transcripts representing 11 out of the 13 CaRab clades could be detected by RT-PCR, but only six ( CaRabA2 , −B , −C , −D , −E and − H ) could be quantified using qRT-PCR due to low expression levels or poor lification efficiency of the degenerate primers for clades containing several gene members. Expression profiles of three gene clades, CaRabB , −D and −E , were very similar across all six chickpea accessions, showing a strongly coordinated network. Salt-induced enhancement of CaRabA2 expression at 15 days showed a very strong positive correlation (R 2 = 0.905) with Na + accumulation in leaves. However, salinity tolerance estimated as relative plant biomass production compared to controls, did not correlate with Na + accumulation in leaves, nor with expression profiles of any of the investigated CaRab -GTP genes. A coordinated network of CaRab-GTP genes, which are likely involved in intracellular trafficking, are important for the salinity stress response of chickpea plants.

The peribacteroid membrane

Publisher: Wiley

Date: 05-1997

DOI: 10.1111/J.1399-3054.1997.TB03452.X

Catabolism of α-Ketoglutarate by a sucA Mutant of Bradyrhizobium japonicum : Evidence for an Alternative Tricarboxylic Acid Cycle

Publisher: American Society for Microbiology

Date: 15-05-2000

DOI: 10.1128/JB.182.10.2838-2844.2000

Abstract: A complete tricarboxylic acid (TCA) cycle is generally considered necessary for energy production from the dicarboxylic acid substrates malate, succinate, and fumarate. However, a Bradyrhizobium japonicum sucA mutant that is missing α-ketoglutarate dehydrogenase is able to grow on malate as its sole source of carbon. This mutant also fixes nitrogen in symbiosis with soybean, where dicarboxylic acids are its principal carbon substrate. Using a flow chamber system to make direct measurements of oxygen consumption and ammonium excretion, we confirmed that bacteroids formed by the sucA mutant displayed wild-type rates of respiration and nitrogen fixation. Despite the absence of α-ketoglutarate dehydrogenase activity, whole cells of the mutant were able to decarboxylate α-[U- 14 C]ketoglutarate and [U- 14 C]glutamate at rates similar to those of wild-type B. japonicum , indicating that there was an alternative route for α-ketoglutarate catabolism. Because cell extracts from B. japonicum decarboxylated [U- 14 C]glutamate very slowly, the γ-aminobutyrate shunt is unlikely to be the pathway responsible for α-ketoglutarate catabolism in the mutant. In contrast, cell extracts from both the wild type and mutant showed a coenzyme A (CoA)-independent α-ketoglutarate decarboxylation activity. This activity was independent of pyridine nucleotides and was stimulated by thiamine PP i . Thin-layer chromatography showed that the product of α-ketoglutarate decarboxylation was succinic semialdehyde. The CoA-independent α-ketoglutarate decarboxylase, along with succinate semialdehyde dehydrogenase, may form an alternative pathway for α-ketoglutarate catabolism, and this pathway may enhance TCA cycle function during symbiotic nitrogen fixation.

Cytoskeletal arrays in the cells of soybean root nodules: The role of actin microfilaments in the organisation of symbiosomes

Publisher: Springer Science and Business Media LLC

Date: 09-1998

DOI: 10.1007/BF01279476

Cloning of an Additional cDNA for the Alternative Oxidase in Tobacco

Publisher: Oxford University Press (OUP)

Date: 04-1995

DOI: 10.1104/PP.107.4.1469

The impact of oxidative stress on Arabidopsis mitochondria

Publisher: Wiley

Date: 12-2002

DOI: 10.1046/J.1365-313X.2002.01474.X

Abstract: Treatment of Arabidopsis cell culture for 16 h with H2O2, menadione or antimycin A induced an oxidative stress decreasing growth rate and increasing DCF fluorescence and lipid peroxidation products. Treated cells remained viable and maintained significant respiratory rates. Mitochondrial integrity was maintained, but accumulation of alternative oxidase and decreased abundance of lipoic acid-containing components during several of the treatments indicated oxidative stress. Analysis of the treatments was undertaken by IEF/SDS-PAGE, comparison of protein spot abundances and tandem mass spectrometry. A set of 25 protein spots increased >3-fold in H2O2/menadione treatments, a subset of these increased in antimycin A-treated s les. A set of 10 protein spots decreased significantly during stress treatments. A specific set of mitochondrial proteins were degraded by stress treatments. These damaged components included subunits of ATP synthase, complex I, succinyl CoA ligase, aconitase, and pyruvate and 2-oxoglutarate dehydrogenase complexes. Nine increased proteins represented products of different genes not found in control mitochondria. One is directly involved in antioxidant defense, a mitochondrial thioredoxin-dependent peroxidase, while another, a thioredoxin reductase-dependent protein disulphide isomerase, is required for protein disulfide redox homeostasis. Several others are generally considered to be extramitochondrial but are clearly present in a highly purified mitochondrial fraction used in this study and are known to play roles in stress response. Using H2O2 as a model stress, further work revealed that this treatment induced a protease activity in isolated mitochondria, putatively responsible for the degradation of oxidatively damaged mitochondrial proteins and that O2 consumption by mitochondria was significantly decreased by H2O2 treatment.

Alternative Oxidase Is Positive for Plant Performance

Publisher: Elsevier BV

Date: 07-2018

DOI: 10.1016/J.TPLANTS.2018.03.012

Abstract: The alternative pathway of mitochondrial electron transport, which terminates in the alternative oxidase (AOX), uncouples oxidation of substrate from mitochondrial ATP production, yet plant performance is improved under adverse growth conditions. AOX is regulated at different levels. Identification of regulatory transcription factors shows that Arabidopsis thaliana AOX1a is under strong transcriptional suppression. At the protein level, the primary structure is not optimised for activity. Maximal activity requires the presence of various metabolites, such as tricarboxylic acid-cycle intermediates that act in an isoform-specific manner. In this opinion article we propose that the regulatory mechanisms that keep AOX activity suppressed, at both the gene and protein level, are positive for plant performance due to the flexible short- and long-term fine-tuning.

Effect of phthalonic acid on respiration and metabolite transport in higher plant mitochondria

Publisher: Elsevier BV

Date: 10-1981

DOI: 10.1016/0003-9861(81)90434-3

Characterisation of Arabidopsis calnexin 1 and calnexin 2 in the endoplasmic reticulum and at plasmodesmata

Publisher: Springer Science and Business Media LLC

Date: 17-12-2017

DOI: 10.1007/S00709-015-0921-3

Abstract: Calnexin (CNX) is a highly conserved endoplasmic reticulum (ER) chaperone protein. Both calnexin and the homologous ER-lumenal protein, calreticulin, bind calcium ions and participate in protein folding. There are two calnexins in Arabidopsis thaliana, CNX1 and CNX2. GUS expression demonstrated that these are expressed in most Arabidopsis tissues throughout development. Calnexin transfer DNA (T-DNA) mutant lines exhibited increased transcript abundances of a number of other ER chaperones, including calreticulins, suggesting a degree of redundancy. CNX1 and CNX2 localised to the ER membrane including that within plasmodesmata, the intercellular channels connecting plant cells. This is comparable with the previous localisations of calreticulin in the ER lumen and at plasmodesmata. However, from green fluorescent protein (GFP) diffusion studies in single and double T-DNA insertion mutant lines, as well as overexpression lines, we found no evidence that CNX1 or CNX2 play a role in intercellular transport through plasmodesmata. In addition, calnexin T-DNA mutant lines showed no change in transcript abundance of a number of plasmodesmata-related proteins. CNX1 and CNX2 do not appear to have a specific localisation or function at plasmodesmata-rather the association of calnexin with the ER is simply maintained as the ER passes through plasmodesmata.

A DICARBOXYLATE TRANSPORTER ON THE PERIBACTEROID MEMBRANE OF SOYBEAN NODULES

Publisher: Wiley

Date: 11-04-1988

DOI: 10.1016/0014-5793(88)80697-5

Cyclin-dependent Kinase E1 (CDKE1) Provides a Cellular Switch in Plants between Growth and Stress Responses

Publisher: Elsevier BV

Date: 02-2013

DOI: 10.1074/JBC.M112.416727

REGULATION OF RESPIRATION IN THE LEAVES AND ROOTS OF 2 LOLIUM-PERENNE POPULATIONS WITH CONTRASTING MATURE LEAF RESPIRATION RATES AND CROP YIELDS

Publisher: Oxford University Press (OUP)

Date: 08-1985

DOI: 10.1104/PP.78.4.678

GmVTL1a is an iron transporter on the symbiosome membrane of soybean with an important role in nitrogen fixation

Publisher: Wiley

Date: 12-07-2020

DOI: 10.1111/NPH.16734

Abstract: Legumes establish symbiotic relationships with soil bacteria (rhizobia), housed in nodules on roots. The plant supplies carbon substrates and other nutrients to the bacteria in exchange for fixed nitrogen. The exchange occurs across a plant‐derived symbiosome membrane (SM), which encloses rhizobia to form a symbiosome. Iron supplied by the plant is crucial for rhizobial enzyme nitrogenase that catalyses nitrogen fixation, but the SM iron transporter has not been identified. We use yeast complementation, real‐time PCR and proteomics to study putative soybean ( Glycine max ) iron transporters GmVTL1a and GmVTL1b and have characterized the role of GmVTL1a using complementation in plant mutants, hairy root transformation and microscopy. GmVTL1a and GmVTL1b are members of the vacuolar iron transporter family and homologous to Lotus japonicus SEN1 (LjSEN1), which is essential for nitrogen fixation. GmVTL1a expression is enhanced in nodule infected cells and both proteins are localized to the SM. GmVTL1a transports iron in yeast and restores nitrogen fixation when expressed in the Ljsen1 mutant. Three GmVTL1a amino acid substitutions that block nitrogen fixation in Ljsen1 plants reduce iron transport in yeast. We conclude GmVTL1a is responsible for transport of iron across the SM to bacteroids and plays a crucial role in the nitrogen‐fixing symbiosis.

Glycine Metabolism and Oxalacetate Transport by Pea Leaf Mitochondria

Publisher: Oxford University Press (OUP)

Date: 08-1981

DOI: 10.1104/PP.68.2.425

A single amino acid change in the plant alternative oxidase alters the specificity of organic acid activation

Publisher: Wiley

Date: 09-07-1999

DOI: 10.1016/S0014-5793(99)00808-X

Abstract: The alternative oxidase is a quinol oxidase of the respiratory chain of plants and some fungi and protists. Its activity is regulated by redox-sensitive disulphide bond formation between neighbouring subunits and direct interaction with certain alpha-ketoacids. To investigate these regulatory mechanisms, we undertook site-directed mutagenesis of soybean and Arabidopsis alternative oxidase cDNAs, and expressed them in tobacco plants and Escherichia coli, respectively. The homologous C99 and C127 residues of GmAOX3 and AtAOX1a, respectively, were changed to serine. In the plant system, this substitution prevented oxidative inactivation of alternative oxidase and rendered the protein insensitive to pyruvate activation, in agreement with the recent results from other laboratories [Rhoads et al. (1998) J. Biol. Chem. 273, 30750-30756 Vanlerberghe et al. (1998) Plant Cell 10, 1551-1560]. However, the mutated protein is instead activated specifically by succinate. Measurements of AtAOX1a activity in bacterial membranes lacking succinate dehydrogenase confirmed that the stimulation of the mutant protein's activity by succinate did not involve its metabolism. Ex les of alternative oxidase proteins with the C to S substitution occur in nature and these oxidases are expected to be activated under most conditions in vivo, with implications for the efficiency of respiration in the tissues which express them.

Soybean Yellow Stripe-like7 is a symbiosome membrane peptide transporter essential for nitrogen fixation

Publisher: Cold Spring Harbor Laboratory

Date: 29-03-2020

DOI: 10.1101/2020.03.27.011973

Abstract: Legumes form a symbiosis with rhizobia that convert atmospheric nitrogen (N 2 ) to ammonia which they provide to the plant in return for a carbon and nutrient supply. Nodules, developed as part of the symbiosis, harbor rhizobia which are enclosed in the plant-derived symbiosome membrane (SM), to form a symbiosome. In the mature nodule all exchanges between the symbionts occur across the SM. Here we characterize GmYSL7, a member of Yellow stripe-like family which is localized to the SM in soybean nodules. It is expressed specifically in nodule infected cells with expression peaking soon after nitrogenase becomes active. Although most members of the family transport metal complexed with phytosiderophores, GmYSL7 does not. It transports oligopeptides of between four and 12 amino acids. Silencing of GmYSL7 reduces nitrogenase activity and blocks development when symbiosomes contain a single bacteroid. RNAseq of nodules in which GmYSL7 is silenced suggests that the plant initiates a defense response against the rhizobia. There is some evidence that metal transport in the nodules is dysregulated, with upregulation of genes encoding ferritin and vacuolar iron transporter family and downregulation of a gene encoding nicotianamine synthase. However, it is not clear whether the changes are a result of the reduction of nitrogen fixation and the requirement to store excess iron or an indication of a role of GmYSL7 in regulation of metal transport in the nodules. Further work to identify the physiological substrate for GmYSL7 will allow clarification of this role. GmYSL7 is a symbiosome membrane peptide transporter that is essential for symbiotic nitrogen fixation that when silenced blocks symbiosome development.

Characterization of Mitochondrial Alternative NAD(P)H Dehydrogenases in Arabidopsis: Intraorganelle Location and Expression

Publisher: Oxford University Press (OUP)

Date: 2006

DOI: 10.1093/PCP/PCI221

Abstract: The intramitochondrial location of putative type II NAD(P)H dehydrogenases (NDs) in Arabidopsis was investigated by measuring the ability of isolated mitochondria to take up precursor proteins generated from cDNAs using an in vitro translation system. The mature proteins of NDA1, NDA2 and NDC1 were judged to be located on the inside of the inner membrane because they were protected from protease added after the mitochondrial outer membrane had been ruptured. In contrast, NDB1, NDB2 and NDB4 were not protected from protease digestion in mitochondria with ruptured outer membranes and were deemed to be located on the outside of the inner membrane. Expression of all ND genes was measured using quantitative reverse transcription-PCR (RT-PCR) to determine transcript abundance, and compared with expression of alternative oxidase, uncoupler proteins and selected components of the oxidative phosphorylation complexes. NDA1 and NDB2 were the most prominently expressed members in a variety of tissues, and were up-regulated in the early daytime in a diurnal manner. Analysis of array data suggested that NDA1 clustered closest to the gene encoding the P-subunit of glycine decarboxylase. Taken together with the diurnal regulation of NDA1 observed here and in other studies, this suggests that NDA1 plays a role in integrating metabolic activities of chloroplasts and mitochondria. NDA2, NDB2 and Aox1a were up-regulated in a coordinated manner under various treatments, potentially forming a complete respiratory chain capable of oxidizing matrix and cytosolic NAD(P)H. NDB1 and NDC1 were down-regulated under the same conditions and may be regarded as housekeeping genes.

Cover Image

Publisher: Wiley

Date: 10-03-2022

DOI: 10.1111/PCE.14306

The regulation of glycolysis and electron transport in roots

Publisher: Wiley

Date: 06-1983

DOI: 10.1111/J.1399-3054.1983.TB04160.X

Dark respiration rates are not determined by differences in mitochondrial capacity, abundance and ultrastructure in C4 leaves

Publisher: Wiley

Date: 06-02-2022

DOI: 10.1111/PCE.14267

Abstract: Our understanding of the regulation of respiration in C 4 plants, where mitochondria play different roles in the different types of C 4 photosynthetic pathway, remains limited. We examined how leaf dark respiration rates ( R dark ), in the presence and absence of added malate, vary in monocots representing the three classical biochemical types of C 4 photosynthesis (NADP‐ME, NAD‐ME and PCK) using intact leaves and extracted bundle sheath strands. In particular, we explored to what extent rates of R dark are associated with mitochondrial number, volume and ultrastructure. Based on examination of a single species per C 4 type, we found that the respiratory response of NAD‐ME and PCK type bundle sheath strands to added malate was associated with differences in mitochondrial number, volume, and/or ultrastructure, while NADP‐ME type bundle sheath strands did not respond to malate addition. In general, mitochondrial traits reflected the contributions mitochondria make to photosynthesis in the three C 4 types. However, despite the obvious differences in mitochondrial traits, no clear correlation was observed between these traits and R dark . We suggest that R dark is primarily driven by cellular maintenance demands and not mitochondrial composition per se, in a manner that is somewhat independent of mitochondrial organic acid cycling in the light.

What makes a mitochondrion?

Publisher: Springer Science and Business Media LLC

Date: 2003

DOI: 10.1186/GB-2003-4-6-218

Identification of intra- and intermolecular disulphide bonding in the plant mitochondrial proteome by diagonal gel electrophoresis

Publisher: Wiley

Date: 11-2007

DOI: 10.1002/PMIC.200700209

Abstract: Redox active proteins in plant mitochondria were examined using 2-D oxidant/reductant diagonal-SDS-PAGE to separate and identify proteins with intermolecular or intramolecular disulphide bonds using diamide in the first dimension and DTT in the second dimension. Eighteen proteins spots were resolved either above or below the diagonal and these were in-gel digested and identified by MS/MS. This analysis revealed intermolecular disulphide bonds in alternative oxidase, O-acetylserine (thiol) lyase, citrate synthase and between subunits of the ATP synthase. Intramolecular disulphide bonds were observed in a range of mitochondrial dehydrogenases, elongation factor Tu, adenylate kinase and the phosphate translocator. Many of the soluble proteins found were known glutaredoxin/thioredoxin targets in other plants, but the membrane proteins were not found by these methods nor were the nature of the disulphides able to be investigated. The accessibility of thiols involved in disulphide bonds to modification by a lipid derived aldehyde gave an insight into the potential impact of Cys modification on redox-functions in mitochondria during lipid peroxidation. Comparison of the protein sequences of the identified proteins with homologs from other species has identified specific Cys residues that may be responsible for plant-specific redox modulations of mitochondrial proteins.

The effect of carboxins on higher plant mitochondria

Publisher: Wiley

Date: 1978

DOI: 10.1016/0014-5793(78)81257-5

Transport processes of the legume symbiosome membrane

Publisher: Frontiers Media SA

Date: 15-12-2014

DOI: 10.3389/FPLS.2014.00699

Malate Transport and Metabolism in Nitrogen-Fixing Legume Nodules

Publisher: MDPI AG

Date: 15-11-2021

DOI: 10.3390/MOLECULES26226876

Abstract: Legumes form a symbiosis with rhizobia, a soil bacterium that allows them to access atmospheric nitrogen and deliver it to the plant for growth. Biological nitrogen fixation occurs in specialized organs, termed nodules, that develop on the legume root system and house nitrogen-fixing rhizobial bacteroids in organelle-like structures termed symbiosomes. The process is highly energetic and there is a large demand for carbon by the bacteroids. This carbon is supplied to the nodule as sucrose, which is broken down in nodule cells to organic acids, principally malate, that can then be assimilated by bacteroids. Sucrose may move through apoplastic and/or symplastic routes to the uninfected cells of the nodule or be directly metabolised at the site of import within the vascular parenchyma cells. Malate must be transported to the infected cells and then across the symbiosome membrane, where it is taken up by bacteroids through a well-characterized dct system. The dicarboxylate transporters on the infected cell and symbiosome membranes have been functionally characterized but remain unidentified. Proteomic and transcriptomic studies have revealed numerous candidates, but more work is required to characterize their function and localise the proteins in planta. GABA, which is present at high concentrations in nodules, may play a regulatory role, but this remains to be explored.

ELECTROGENIC ATPASE ACTIVITY ON THE PERIBACTEROID MEMBRANE OF SOYBEAN (GLYCINE-MAX L) ROOT-NODULES

Publisher: Oxford University Press (OUP)

Date: 07-1989

DOI: 10.1104/PP.90.3.982

Analysis of Respiratory Chain Regulation in Roots of Soybean Seedlings1

Publisher: Oxford University Press (OUP)

Date: 07-1998

DOI: 10.1104/PP.117.3.1083

Abstract: Changes in the respiratory rate and the contribution of the cytochrome (Cyt) c oxidase and alternative oxidase (COX and AOX, respectively) were investigated in soybean (Glycine max L. cv Stevens) root seedlings using the 18O-discrimination method. In 4-d-old roots respiration proceeded almost entirely via COX, but by d 17 more than 50% of the flux occurred via AOX. During this period the capacity of COX, the theoretical yield of ATP synthesis, and the root relative growth rate all decreased substantially. In extracts from whole roots of different ages, the ubiquinone pool was maintained at 50% to 60% reduction, whereas pyruvate content fluctuated without a consistent trend. In whole-root immunoblots, AOX protein was largely in the reduced, active form at 7 and 17 d but was partially oxidized at 4 d. In isolated mitochondria, Cyt pathway and succinate dehydrogenase capacities and COX I protein abundance decreased with root age, whereas both AOX capacity and protein abundance remained unchanged. The amount of mitochondrial protein on a dry-mass basis did not vary significantly with root age. It is concluded that decreases in whole-root respiration during growth of soybean seedlings can be largely explained by decreases in maximal rates of electron transport via COX. Flux via AOX is increased so that the ubiquinone pool is maintained in a moderately reduced state.

Plant Mitochondria

Publisher: Springer New York

Date: 2015

DOI: 10.1007/978-1-4939-2639-8

Identification of AtNDI1, an Internal Non-Phosphorylating NAD(P)H Dehydrogenase in Arabidopsis Mitochondria

Publisher: Oxford University Press (OUP)

Date: 12-2003

DOI: 10.1104/PP.103.029363

Abstract: Plant mitochondria contain non-phosphorylating NAD(P)H dehydrogenases (DHs) that are not found in animal mitochondria. The physiological function, substrate specificity, and location of enzymes within this family have yet to be conclusively determined. We have linked genome sequence information to protein and biochemical data to identify that At1g07180 (SwissProt Q8GWA1) from the Arabidopsis Genome Initiative database encodes AtNDI1, an internal NAD(P)H DH in Arabidopsis mitochondria. Three lines of evidence are presented: (a) The predicted protein sequence of AtNDI1 has high homology with other designated NAD(P)H DHs from microorganisms, (b) the capacity for matrix NAD(P)H oxidation via the rotenone-insensitive pathway is significantly reduced in the Atndi1 mutant plant line, and (c) the in vitro translation product of AtNDI1 is imported into isolated mitochondria and located on the inside of the inner membrane.

Experimental Analysis of the Arabidopsis Mitochondrial Proteome Highlights Signaling and Regulatory Components, Provides Assessment of Targeting Prediction Programs, and Indicates Plant-Specific Mitoc

Publisher: Oxford University Press (OUP)

Date: 2004

DOI: 10.1105/TPC.016055

Abstract: A novel insight into Arabidopsis mitochondrial function was revealed from a large experimental proteome derived by liquid chromatography–tandem mass spectrometry. Within the experimental set of 416 identified proteins, a significant number of low-abundance proteins involved in DNA synthesis, transcriptional regulation, protein complex assembly, and cellular signaling were discovered. Nearly 20% of the experimentally identified proteins are of unknown function, suggesting a wealth of undiscovered mitochondrial functions in plants. Only approximately half of the experimental set is predicted to be mitochondrial by targeting prediction programs, allowing an assessment of the benefits and limitations of these programs in determining plant mitochondrial proteomes. Maps of putative orthology networks between yeast, human, and Arabidopsis mitochondrial proteomes and the Rickettsia prowazekii proteome provide detailed insights into the ergence of the plant mitochondrial proteome from those of other eukaryotes. These show a clear set of putative cross-species orthologs in the core metabolic functions of mitochondria, whereas considerable ersity exists in many signaling and regulatory functions.

Sensitivity of plant mitochondrial terminal oxidases to the lipid peroxidation product 4-hydroxy-2-nonenal (HNE)

Publisher: Portland Press Ltd.

Date: 26-04-2005

DOI: 10.1042/BJ20042044

Abstract: We have investigated the effect of the lipid peroxidation product, HNE (4-hydroxy-2-nonenal), on plant mitochondrial electron transport. In mitochondria isolated from Arabidopsis thaliana cell cultures, HNE inhibited succinate-dependent oxygen consumption via the Aox (alternative oxidase), but had minimal effect on respiration via Cox (cytochrome c oxidase). Maximal Cox activity, measured with reduced cytochrome c as substrate, was only slightly inhibited by high concentrations of HNE, at which Aox was completely inhibited. Incubation with HNE prevented dimerization of the Aox protein, suggesting that one site of modification was the conserved cysteine residue involved in dimerization and activation of this enzyme (CysI). However, a naturally occurring isoform of Aox lacking CysI and unable to be dimerized, LeAox1b from tomato (Lycopersicon esculentum), was equally sensitive to HNE inhibition, showing that other amino acid residues in Aox also interact with HNE. The presence of HNE in vivo in Arabidopsis cell cultures was also investigated. Induction of oxidative stress in the cell cultures by the addition of hydrogen peroxide, antimycin A or menadione, caused a significant increase in hydroxyalkenals (of which HNE is the most prominent). Western blotting of mitochondrial proteins with antibodies against HNE adducts, demonstrated significant modification of proteins during these treatments. The implications of these results for the response of plants to reactive oxygen species are discussed.

Salicylic acid is an uncoupler and inhibitor of mitochondrial electron transport

Publisher: Oxford University Press (OUP)

Date: 2004

DOI: 10.1104/PP.103.031039

Abstract: The effect of salicylic acid (SA) on respiration and mitochondrial function was examined in tobacco (Nicotiana tabacum) suspension cell cultures in the range of 0.01 to 5 mm. Cells rapidly accumulated SA up to 10-fold of the externally applied concentrations. At the lower concentrations, SA accumulation was transitory. When applied at 0.1 mm or less, SA stimulated respiration of whole cells and isolated mitochondria in the absence of added ADP, indicating uncoupling of respiration. However, at higher concentrations, respiration was severely inhibited. Measurements of ubiquinone redox poise in isolated mitochondria suggested that SA blocked electron flow from the substrate dehydrogenases to the ubiquinone pool. This inhibition could be at least partially reversed by re-isolating the mitochondria. Two active analogs of SA, benzoic acid and acetyl-SA, had the same effect as SA on isolated tobacco mitochondria, whereas the inactive p-hydroxybenzoic acid was without effect at the same concentration. SA induced an increase in Aox protein levels in cell suspensions, and this was correlated with an increase in Aox1 transcript abundance. However, when applied at 0.1 mm, this induction was transient and disappeared as SA levels in the cells declined. SA at 0.1 mm also increased the expression of other SA-responsive genes, and this induction was dependent on active mitochondria. The results indicate that SA is both an uncoupler and an inhibitor of mitochondrial electron transport and suggest that this underlies the induction of some genes by SA. The possible implications of this for the interpretation of SA action in plants are discussed.

Characterization of the Import Pathway of the FAd Subunit of Mitochondrial ATP Synthase into Isolated Plant Mitochondria

Publisher: Elsevier BV

Date: 11-1996

DOI: 10.1006/ABBI.1996.0517

Abstract: The synthetic precursor of the F(A)d subunit of mitochondrial ATP synthase was imported into isolated soybean cotyledon mitochondria. Import of the F(A)d precursor was accompanied by processing to a lower molecular weight mature form. The F(A)d precursor displayed the following import characteristics not seen before with plant mitochondria: efficient import in the absence of external ATP and import of wheat germ-translated precursor. Pretreatment of the F(A)d precursor with NEM did not inhibit import. Taken together with the lack of a requirement for external ATP, this indicates that this precursor does not require extramitochondrial ATP-dependent factors for import. Binding studies indicated that the F(A)d precursor bound to a proteinaceous component of the mitochondrial outer membrane. Inhibitor studies indicated that processing was most likely via the general mitochondrial processing peptidase. The results suggest that import of this subunit occurs via a pathway different from the general import pathway described for the majority of precursor proteins.

Regulation of Alternative Pathway Activity in Plant Mitochondria

Publisher: Oxford University Press (OUP)

Date: 03-1991

DOI: 10.1104/PP.95.3.948

Iron: an essential micronutrient for the legume-rhizobium symbiosis

Publisher: Frontiers Media SA

Date: 2013

DOI: 10.3389/FPLS.2013.00359

Relationship between autoregulation and nitrate inhibition of nodulation in soybeans

Publisher: Wiley

Date: 1989

DOI: 10.1111/J.1399-3054.1989.TB02060.X

Enzymes of Ammonia Assimilation and Ureide Biosynthesis in Soybean Nodules: Effect of Nitrate

Publisher: Oxford University Press (OUP)

Date: 03-1986

DOI: 10.1104/PP.80.3.646

GmZIP1 encodes a symbiosis-specific zinc transporter in soybean

Publisher: Elsevier BV

Date: 02-2002

DOI: 10.1074/JBC.M106754200

Characterization of an ammonium transport protein from the peribacteroid membrane of soybean nodules

Publisher: American Association for the Advancement of Science (AAAS)

Date: 21-08-1998

DOI: 10.1126/SCIENCE.281.5380.1202

Abstract: Nitrogen-fixing bacteroids in legume root nodules are surrounded by the plant-derived peribacteroid membrane, which controls nutrient transfer between the symbionts. A nodule complementary DNA ( GmSAT1 ) encoding an ammonium transporter has been isolated from soybean. GmSAT1 is preferentially transcribed in nodules and immunoblotting indicates that GmSAT1 is located on the peribacteroid membrane. [ 14 C]methylammonium uptake and patch-cl analysis of yeast expressing GmSAT1 demonstrated that it shares properties with a soybean peribacteroid membrane NH 4 + channel described elsewhere. GmSAT1 is likely to be involved in the transfer of fixed nitrogen from the bacteroid to the host.

Regulation of the Soybean-Rhizobium Nodule Symbiosis by Shoot and Root Factors

Publisher: Oxford University Press (OUP)

Date: 10-1986

DOI: 10.1104/PP.82.2.588

Aspartate and alanine movement across symbiotic membranes of soybean nodules

Publisher: Elsevier BV

Date: 10-1998

DOI: 10.1016/S0038-0717(97)00229-0

Rotenone-Insensitive Malate Oxidation by Isolated Plant Mitochondria

Publisher: Oxford University Press (OUP)

Date: 1979

DOI: 10.1093/JXB/30.1.99

Dicarboxylate transport in maize mesophyll chloroplasts

Publisher: Elsevier BV

Date: 10-1981

DOI: 10.1016/0003-9861(81)90510-5

Abstract: The development of disease-modifying therapies for Alzheimer's disease is an urgent public health emergency. Recent failures have highlighted the significant challenges faced by drug-development programs. Longitudinal cohort studies are ideal for promoting understanding of this multifactorial, slowly progressive disease. In this section of the special edition, we review several important lessons from longitudinal cohort studies which should be considered in disease-modifying therapy development. In the final section, we introduce the clinical cohort of the Center for Neurodegeneration and Translational Neuroscience. This newly established longitudinal study aims to provide new insights into the neuroimaging and biological marker (biomarkers) correlates of cognitive decline in early Alzheimer's disease and Parkinson's disease (PD).

The cytotoxic lipid peroxidation product 4-hydroxy-2-nonenal covalently modifies a selective range of proteins linked to respiratory function in plant mitochondria

Publisher: Elsevier BV

Date: 12-2007

DOI: 10.1074/JBC.M702385200

Induction of alternative oxidase synthesis by herbicides inhibiting branched‐chain amino acid synthesis

Publisher: Wiley

Date: 04-1997

DOI: 10.1046/J.1365-313X.1997.11040649.X

How is leghemoglobin involved in peribacteroid membrane degradation during nodule senescence?

Publisher: Wiley

Date: 07-1993

DOI: 10.1016/0014-5793(93)81755-O

Abstract: An increase in the rate of succinate and glutamate uptake by isolated symbiosomes from French bean nodules was observed in the presence of iron plus H2O2. The lipid bilayer, and not proteins involved in transport, seems to be the major target of radical attack. Leghemoglobin in the presence of a 6-fold excess of H2O2 (where heme breakdown and iron release occurred) provoked also an increase in peribacteroid membrane permeability. In contrast, this hemoprotein in the presence of a 2-fold excess of H2O2 (where a protein radical was generated) was without effect. We suggest that in vivo the release of heme iron may constitute the major process concerning the involvement of leghemoglobin in the degradation of the peribacteroid membrane during nodule senescence.

Studies on the import and processing of the alternative oxidase precursor by isolated soybean mitochondria

Publisher: Springer Science and Business Media LLC

Date: 02-1995

DOI: 10.1007/BF00020229

Proteomic Analysis of the Soybean Symbiosome Identifies New Symbiotic Proteins

Publisher: Elsevier BV

Date: 05-2015

DOI: 10.1074/MCP.M114.043166

Analysis of the Alternative Oxidase Promoters from Soybean

Publisher: Oxford University Press (OUP)

Date: 11-2003

DOI: 10.1104/PP.103.028183

Abstract: Alternative oxidase (Aox) is a nuclear-encoded mitochondrial protein. In soybean (Glycine max), the three members of the gene family have been shown to be differentially expressed during normal plant development and in response to stresses. To examine the function of the Aox promoters, genomic fragments were obtained for all three soybean genes: Aox1, Aox2a, and Aox2b. The regions of these fragments immediately upstream of the coding regions were used to drive β-glucuronidase (GUS) expression during transient transformation of soybean suspension culture cells and stable transformation of Arabidopsis. The expression patterns of the GUS reporter genes in soybean cells were in agreement with the presence or absence of the various endogenous Aox proteins, determined by immunoblotting. Deletion of different portions of the upstream regions identified sequences responsible for both positive and negative regulation of Aox gene expression in soybean cells. Reporter gene analysis in Arabidopsis plants showed differential tissue expression patterns driven by the three upstream regions, similar to those reported for the endogenous proteins in soybean. The expression profiles of all five members of the Arabidopsis Aox gene family were examined also, to compare with GUS expression driven by the soybean upstream fragments. Even though the promoter activity of the upstream fragments from soybean Aox2a and Aox2b displayed the same tissue specificity in Arabidopsis as they do in soybean, the most prominently expressed endogenous genes in all tissues of Arabidopsis were of the Aox1 type. Thus although regulation of Aox expression generally appears to involve the same signals in different species, different orthologs of Aox may respond variously to these signals. A comparison of upstream sequences between soybean Aox genes and similarly expressed Arabidopsis Aox genes identified common motifs.

Energy costs of salt tolerance in crop plants

Publisher: Wiley

Date: 11-07-2019

DOI: 10.1111/NPH.15864

Abstract: Agriculture is expanding into regions that are affected by salinity. This review considers the energetic costs of salinity tolerance in crop plants and provides a framework for a quantitative assessment of costs. Different sources of energy, and modifications of root system architecture that would maximize water vs ion uptake are addressed. Energy requirements for transport of salt (NaCl) to leaf vacuoles for osmotic adjustment could be small if there are no substantial leaks back across plasma membrane and tonoplast in root and leaf. The coupling ratio of the H

Legume Alternative Oxidase Isoforms Show Differential Sensitivity to Pyruvate Activation

Publisher: Frontiers Media SA

Date: 17-01-2022

DOI: 10.3389/FPLS.2021.813691

Abstract: Alternative oxidase (AOX) is an important component of the plant respiratory pathway, enabling a route for electrons that bypasses the energy-conserving, ROS-producing complexes of the mitochondrial electron transport chain. Plants contain numerous isoforms of AOX, classified as either AOX1 or AOX2. AOX1 isoforms have received the most attention due to their importance in stress responses across a wide range of species. However, the propensity for at least one isoform of AOX2 to accumulate to very high levels in photosynthetic tissues of all legumes studied to date, suggests that this isoform has specialized roles, but we know little of its properties. Previous studies with sub-mitochondrial particles of soybean cotyledons and roots indicated that differential expression of GmAOX1, GmAOX2A, and GmAOX2D across tissues might confer different activation kinetics with pyruvate. We have investigated this using recombinantly expressed isoforms of soybean AOX in a previously described bacterial system ( Selinski et al., 2016 , Physiologia Plantarum 157, 264-279). Pyruvate activation kinetics were similar between the two GmAOX2 isoforms but differed substantially from those of GmAOX1, suggesting that selective expression of AOX1 and 2 could determine the level of AOX activity. However, this alone cannot completely explain the differences seen in sub-mitochondrial particles isolated from different legume tissues and possible reasons for this are discussed.

Alternative Oxidase Isoforms Are Differentially Activated by Tricarboxylic Acid Cycle Intermediates

Publisher: Oxford University Press (OUP)

Date: 05-12-2017

DOI: 10.1104/PP.17.01331

Effect of Phosphate and Uncouplers on Substrate Transport and Oxidation by Isolated Corn Mitochondria

Publisher: Oxford University Press (OUP)

Date: 02-1977

DOI: 10.1104/PP.59.2.139

The Absence of Alternative Oxidase AOX1A Results in Altered Response of Photosynthetic Carbon Assimilation to Increasing CO2 in Arabidopsis thaliana

Publisher: Oxford University Press (OUP)

Date: 30-07-2012

DOI: 10.1093/PCP/PCS107

Abstract: In higher plants, the mitochondrial electron transport chain has non-phosphorylating alternative pathways that include the alternative terminal oxidase (AOX). This alternative pathway has been suggested to act as a sink for dissipating excess reducing power, minimizing oxidative stress and possibly optimizing photosynthesis in response to changing conditions. The expression patterns of the AOX genes have been well characterized under different growth conditions, particularly in response to light and temperature stress. Additionally, it has been suggested that mitochondrial electron transport is important for avoiding chloroplast over-reduction and balancing energy partitioning among photosynthesis, photorespiration and respiration. Nonetheless, the role AOX plays in optimizing photosynthetic carbon metabolism is unclear. Therefore, the response of photosynthesis to the disruption of AOX was investigated in the Arabidopsis thaliana T-DNA mutant aox1a (SALK_084897). Gas exchange analysis revealed a lower net CO(2) assimilation rate (A) at high CO(2) concentrations in the aox1a mutant compared to wild type. This decrease in A was accompanied by a lower maximum electron transport rate and quantum yield of PSII, and higher excitation pressure on PSII and non-photochemical quenching. The aox1a mutant also exhibited a lower estimated rate of ribulose 1,5-bisphosphate regeneration, and the ribulose 1,5-bisphosphate content was lower at high CO(2) concentrations, suggesting an ATP limitation of the Calvin-Benson cycle. Additionally, the activity of the malate-oxaloacetate shuttle was lower in the mutant compared to wild type. These results indicate that AOX is important for optimizing rates of photosynthetic CO(2) assimilation in response to rising CO(2) concentration by balancing the NAD(P)H/ATP ratio and rates of ribulose 1,5-bisphosphate regeneration within the chloroplast.

Response of mitochondria to light intensity in the leaves of sun and shade species

Publisher: Wiley

Date: 09-03-2005

DOI: 10.1111/J.1365-3040.2005.01322.X

On methods for the isolation of mitochondria from etiolated corn shoots

Publisher: Elsevier BV

Date: 02-1978

DOI: 10.1016/0304-4211(78)90112-8

The Oxidation of Malate and Exogenous Reduced Nicotinamide Adenine Dinucleotide by Isolated Plant Mitochondria

Publisher: Oxford University Press (OUP)

Date: 1974

DOI: 10.1104/PP.53.1.104

Maintenance of growth rate at low temperature in rice and wheat cultivars with a high degree of respiratory homeostasis is associated with a high efficiency of respiratory ATP production

Publisher: Oxford University Press (OUP)

Date: 15-08-2004

DOI: 10.1093/PCP/PCH116

The crucial roles of mitochondria in supporting C₄ photosynthesis

Publisher: Wiley

Date: 13-11-2021

DOI: 10.1111/NPH.17818

Abstract: C 4 photosynthesis involves a series of biochemical and anatomical traits that significantly improve plant productivity under conditions that reduce the efficiency of C 3 photosynthesis. We explore how evolution of the three classical biochemical types of C 4 photosynthesis (NADP‐ME, NAD‐ME and PCK types) has affected the functions and properties of mitochondria. Mitochondria in C 4 NAD‐ME and PCK types play a direct role in decarboxylation of metabolites for C 4 photosynthesis. Mitochondria in C 4 PCK type also provide ATP for C 4 metabolism, although this role for ATP provision is not seen in NAD‐ME type. Such involvement has increased mitochondrial abundance/size and associated enzymatic capacity, led to changes in mitochondrial location and ultrastructure, and altered the role of mitochondria in cellular carbon metabolism in the NAD‐ME and PCK types. By contrast, these changes in mitochondrial properties are absent in the C 4 NADP‐ME type and C 3 leaves, where mitochondria play no direct role in photosynthesis. From an eco‐physiological perspective, rates of leaf respiration in darkness vary considerably among C 4 species but does not differ systematically among the three C 4 types. This review outlines further mitochondrial research in key areas central to the engineering of the C 4 pathway into C 3 plants and to the understanding of variation in rates of C 4 dark respiration.

Isolation and Respiratory Measurements of Mitochondria from <em>Arabidopsis thaliana</em>

Publisher: MyJove Corporation

Date: 05-01-2018

DOI: 10.3791/56627

Malate Oxidation, Rotenone-Resistance, and Alternative Path Activity in Plant Mitochondria

Publisher: Oxford University Press (OUP)

Date: 10-1982

DOI: 10.1104/PP.70.4.959

Isolation and oxidative properties of mitochondria and bacteroids from soybean root nodules

Publisher: Springer Science and Business Media LLC

Date: 06-1986

DOI: 10.1007/BF01275710

Effect of respiratory homeostasis on plant growth in cultivars of wheat and rice

Publisher: Wiley

Date: 07-05-2004

DOI: 10.1111/J.1365-3040.2004.01191.X

Mechanism of soybean nodule adaptation to different oxygen pressures

Publisher: Wiley

Date: 08-1990

DOI: 10.1111/J.1365-3040.1990.TB01066.X

Exogenous NAD⁺ Effects on Plant Mitochondria

Publisher: Oxford University Press (OUP)

Date: 12-1983

DOI: 10.1104/PP.73.4.1024

Organization and Regulation of Mitochondrial Respiration in Plants

Publisher: Annual Reviews

Date: 02-06-2011

DOI: 10.1146/ANNUREV-ARPLANT-042110-103857

Abstract: Mitochondrial respiration in plants provides energy for biosynthesis, and its balance with photosynthesis determines the rate of plant biomass accumulation. We describe recent advances in our understanding of the mitochondrial respiratory machinery of cells, including the presence of a classical oxidative phosphorylation system linked to the cytosol by transporters, discussed alongside nonphosphorylating (and, therefore, non-energy conserving) bypasses that alter the efficiency of ATP synthesis and play a role in oxidative stress responses in plants. We consider respiratory regulation in the context of the contrasting roles mitochondria play in different tissues, from photosynthetic leaves to nutrient-acquiring roots. We focus on the molecular nature of this regulation at transcriptional and post-transcriptional levels that allow the respiratory apparatus of plants to help shape organ development and the response of plants to environmental stress. We highlight the challenges for future research considering spatial and temporal changes of respiration in response to changing climatic conditions.

Activation of NAD-linked malic enzyme in intact plant mitochondria by exogenous coenzyme A

Publisher: Elsevier BV

Date: 05-1984

DOI: 10.1016/0003-9861(84)90383-7

Abstract: O2 uptake by potato and cauliflower bud mitochondria oxidizing malate was progressively inhibited as the pH of the external medium was increased, in response to accumulation of oxaloacetate. Adding 0.5 mM coenzyme A to the medium reversed this trend by stimulating intramitochondrial NAD-linked malic enzyme at alkaline pH. In intact potato mitochondria, coenzyme A stimulation of malic enzyme was not observed when the external pH was above 7.5 in cauliflower mitochondria, coenzyme A stimulated even at pH 8. This difference in the response of intact mitochondria was attributed to an inherent difference in the properties of malic enzyme from the two tissues. Malic enzyme solubilized from potato mitochondria was inactive at pH values above 7.8, while that from cauliflower mitochondria retained its activity at pH 8 in the presence of coenzyme A. In potato mitochondria, coenzyme A stimulation of O2 uptake at alkaline pH was only observed when NAD+ was also provided exogenously. The results show that coenzyme A can be taken up by intact mitochondria and that pH, NAD+, and coenzyme A levels in the matrix act together to regulate malate oxidation.

A matrix-located processing peptidase of plant mitochondria

Publisher: Springer Science and Business Media LLC

Date: 1998

DOI: 10.1023/A:1005977716814

Abstract: Nuclear-encoded mitochondrial precursor proteins are proteolytically processed inside the mitochondrion after import. The general mitochondrial processing activity in plant mitochondria has been shown to be integrated into the cytochrome bc1 complex of the respiratory chain. Here we investigate the occurrence of an additional, matrix-located processing activity by incubation of the precursors of the soybean mitochondrial proteins, alternative oxidase, the FAd subunit of the ATP synthetase and the tobacco F1 beta subunit of the ATP synthase, with the membrane and soluble components of mitochondria isolated from soybean cotyledons and spinach leaves. A matrix-located peptidase specifically processed the precursors to the predicted mature form in a reaction which was sensitive to orthophenanthroline, a characteristic inhibitor of mitochondrial processing peptidase (MPP). The specificity of the matrix peptidase was illustrated by the inhibition of processing of the alternative oxidase precursor in both soybean and spinach matrix extracts upon altering a single amino acid residue in the targeting presequence (-2 Arg to Gly). Additionally, there was no evidence for general proteolysis of precursor proteins incubated with the matrix. The purity of the matrix fractions was ascertained by spectrophotometric and immunological analyses. The results demonstrate that there is a specific processing activity in the matrix of soybean and spinach in addition to the previously well characterized membrane-bound MPP integrated into the cytochrome bcl complex of the respiratory chain.

Evidence for Metabolic Domains within the Matrix Compartment of Pea Leaf Mitochondria

Publisher: Oxford University Press (OUP)

Date: 06-1990

DOI: 10.1104/PP.93.2.611

Ferrous iron is transported across the peribacteroid membrane of soybean nodules

Publisher: Springer Science and Business Media LLC

Date: 12-11-1998

DOI: 10.1007/S004250050458

Cloning of ndhK from soybean chloroplasts using antibodies raised to mitochondrial complex I

Publisher: Springer Science and Business Media LLC

Date: 12-1992

DOI: 10.1007/BF00027160

Abstract: The cardiovascular effects of adimolol, a new, potent, long acting beta-adrenoceptor blocking drug were investigated in three studies. In the first study blood pressure and heart rate were measured in five male volunteers before and at 2, 4, 6, 8, 24, 32, 48, 72 and 96 h after single oral doses of adimolol. All doses of adimolol reduced supine, standing and exercise heart rates in a dose dependent manner. The maximum effect ranged from 18% following 25 mg to 29% following 600 mg and all doses showed an effect at 96 h (range 3.5-17.2%). In the second study the effects of adimolol, 25 and 400 mg, labetalol, 200 and 800 mg, propranolol 40 mg and placebo were compared on supine and standing heart rate and blood pressure and on exercise heart rate before and at 2, 4, 6 and 8 h after single oral doses. The exercise heart rate was significantly reduced at all times following adimolol 25 and 400 mg, labetalol 800 mg and propranolol 40 mg. At 2 h all the drugs significantly reduced standing systolic blood pressure. In the third study, 4 h after single oral doses of adimolol 400 mg, labetalol 400 mg and propranolol 40 mg six subjects received serial 4 min infusions of phenylephrine. The blood pressure was measured after each infusion. Labetalol 400 mg significantly shifted the blood pressure dose-response curve to the right. There was no difference between propranolol 40 mg and adimolol 400 mg. These studies show that adimolol is a potent, long acting beta-adrenoceptor blocking drug without evidence of alpha-adrenoceptor blockade in man.

Molecular and physiological responses during thermal acclimation of leaf photosynthesis and respiration in rice.

Publisher: Wiley

Date: 10-01-2020

DOI: 10.1111/PCE.13706

Abstract: To further our understanding of how sustained changes in temperature affect the carbon economy of rice (Oryza sativa), hydroponically grown plants of the IR64 cultivar were developed at 30°C/25°C (day/night) before being shifted to 25/20°C or 40/35°C. Leaf messenger RNA and protein abundance, sugar and starch concentrations, and gas-exchange and elongation rates were measured on preexisting leaves (PE) already developed at 30/25°C or leaves newly developed (ND) subsequent to temperature transfer. Following a shift in growth temperature, there was a transient adjustment in metabolic gene transcript abundance of PE leaves before homoeostasis was reached within 24 hr, aligning with R

Transport of 3-phosphoglyceric acid, phosphoenolpyruvate, and inorganic phosphate in maize mesophyll chloroplasts, and the effect of 3-phosphoglyceric acid on malate and phosphoenolpyruvate production

Publisher: Elsevier BV

Date: 10-1981

DOI: 10.1016/0003-9861(81)90511-7

Abstract: This study investigated the effect of traditional and improved solar drying methods on the sensory quality and nutritional composition of the dried fruit products using mangoes and pineapples, as a case study. The fruits were dried under five solar drying methods namely open sun drying (OSD), black-cloth shade (BCS), white-cloth shade (WCS), a conventional solar dryer (CSD), and a newly improved solar dryer (ISD) technology. The ISD unit was made of a modified solar concentrator plate containing multiple metallic solar collectors arranged in series. The ISD drying cabinet was also enclosed with a specialized greenhouse cover materials. The drying operations were conducted following a completely randomized design (CRD) experimental procedure. The mean drying air temperatures for the OSD, BCS, WCS, CSD and ISD methods were 26.8, 26.7, 24.5, 32.6 and 40.3 °C respectively. Results showed that the five solar drying methods were capable of retaining the sensory quality and nutritional composition of dried mango and pineapples. The nutritional parameters retained were proximate and mineral content. The sensory quality parameters were taste, aroma, colour and acceptability of the dried fruit products. However, the sensory quality and nutritional content of the fruit products dried under the ISD method were higher than that of the products dried under the CSD method, suggesting an enhanced capacity and superior role of the ISD dryer technology in fruit processing. The ISD technology was, therefore, recommended as a better fruit drying method than the traditional solar drying methods. Using the ISD method could be a feasible solution and a strategic pathway to addressing the high post-harvest losses of fruits as well as other perishable fresh produce in East Africa.

AMMONIA (C-14-METHYLAMINE) TRANSPORT ACROSS THE BACTEROID AND PERIBACTEROID MEMBRANES OF SOYBEAN ROOT-NODULES

Publisher: Oxford University Press (OUP)

Date: 09-1990

DOI: 10.1104/PP.94.1.71

ATPASE ACTIVITY AND ANION TRANSPORT ACROSS THE PERIBACTEROID MEMBRANE OF ISOLATED SOYBEAN SYMBIOSOMES

Publisher: Springer Science and Business Media LLC

Date: 10-1991

DOI: 10.1007/BF00248711

Nitrogenase activity and ureide levels in a supernodulating soybean mutant: Effects of inoculum dose and nitrate treatment

Publisher: Wiley

Date: 09-1988

DOI: 10.1111/J.1399-3054.1988.TB04942.X

Evidence for a link between translocation and processing during protein import into soybean mitochondria

Publisher: Elsevier BV

Date: 06-1996

DOI: 10.1016/0167-4889(96)00014-6

Abstract: The effect of metal chelators on protein import was investigated using isolated soybean mitochondria and soybean precursor proteins. Adding 1,10-phenanthroline, a metal chelator that can cross both mitochondrial membranes abolished import of both the alternative oxidase, and the F(A)d subunit of the ATP synthase, a matrix located protein. Other metal chelators such as EDTA, 1,7-phenanthroline and 4,7-phenanthroline, which cannot cross the mitochondrial membranes, had no effect on import. When processing, a known metal-dependent step inside mitochondria, was inhibited using a mutagenesis approach (changing a -2 arginine to a -2 glycine in the pre-piece of the precursor), so was import. Thus it would appear that in soybean, at least, translocation of proteins across the mitochondrial membrane, as well as processing, relies on a metal dependent step. Taken together, the data suggest the two processes may be directly connected in these mitochondria.

Targets of stress-induced oxidative damage in plant mitochondria and their impact on cell carbon/nitrogen metabolism

Publisher: Oxford University Press (OUP)

Date: 28-11-2004

DOI: 10.1093/JXB/ERH001

Identification and Characterization of an Inducible NAD(P)H Dehydrogenase from Red Beetroot Mitochondria

Publisher: Oxford University Press (OUP)

Date: 10-1996

DOI: 10.1104/PP.112.2.607

Abstract: Exogenous NADH oxidation of mitochondria isolated from red beetroots (Beta vulgaris L.) increased dramatically upon slicing and aging the tissue. Anion-exchange chromatography of soluble fractions derived by sonication from fresh and aged beetroot mitochondria yielded three NADH dehydrogenase activity peaks. The third peak from aged beetroot mitochondria was separated into two activities by blue-affinity chromatography. One of these (the unbound peak) readily oxidized dihydrolipoamide, whereas the other (the bound peak) did not. The latter was an NAD(P)H dehydrogenase with high quinone and ferricyanide reductase activity and was absent from fresh beet mitochondria. Further affinity chromatography of the NAD(P)H dehydrogenase indicated enrichment of a 58-kD polypeptide on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We propose that this 58-kD protein is the inducible, external NADH dehydrogenase.

Identification of alternative mitochondrial electron transport pathway components in chickpea indicates a differential response to salinity stress between cultivars

Publisher: MDPI AG

Date: 28-05-2020

DOI: 10.3390/IJMS21113844

Abstract: All plants contain an alternative electron transport pathway (AP) in their mitochondria, consisting of the alternative oxidase (AOX) and type 2 NAD(P)H dehydrogenase (ND) families, that are thought to play a role in controlling oxidative stress responses at the cellular level. These alternative electron transport components have been extensively studied in plants like Arabidopsis and stress inducible isoforms identified, but we know very little about them in the important crop plant chickpea. Here we identify AP components in chickpea (Cicer arietinum) and explore their response to stress at the transcript level. Based on sequence similarity with the functionally characterized proteins of Arabidopsis thaliana, five putative internal (matrix)-facing NAD(P)H dehydrogenases (CaNDA1-4 and CaNDC1) and four putative external (inter-membrane space)-facing NAD(P)H dehydrogenases (CaNDB1-4) were identified in chickpea. The corresponding activities were demonstrated for the first time in purified mitochondria of chickpea leaves and roots. Oxidation of matrix NADH generated from malate or glycine in the presence of the Complex I inhibitor rotenone was high compared to other plant species, as was oxidation of exogenous NAD(P)H. In leaf mitochondria, external NADH oxidation was stimulated by exogenous calcium and external NADPH oxidation was essentially calcium dependent. However, in roots these activities were low and largely calcium independent. A salinity experiment with six chickpea cultivars was used to identify salt-responsive alternative oxidase and NAD(P)H dehydrogenase gene transcripts in leaves from a three-point time series. An analysis of the Na:K ratio and Na content separated these cultivars into high and low Na accumulators. In the high Na accumulators, there was a significant up-regulation of CaAOX1, CaNDB2, CaNDB4, CaNDA3 and CaNDC1 in leaf tissue under long term stress, suggesting the formation of a stress-modified form of the mitochondrial electron transport chain (mETC) in leaves of these cultivars. In particular, stress-induced expression of the CaNDB2 gene showed a striking positive correlation with that of CaAOX1 across all genotypes and time points. The coordinated salinity-induced up-regulation of CaAOX1 and CaNDB2 suggests that the mitochondrial alternative pathway of respiration is an important facet of the stress response in chickpea, in high Na accumulators in particular, despite high capacities for both of these activities in leaf mitochondria of non-stressed chickpeas.

Effect of Ethylene and Carbon Dioxide on Potato Metabolism

Publisher: Oxford University Press (OUP)

Date: 11-1978

DOI: 10.1104/PP.62.5.820

Isolation of a Novel Soybean Gene Encoding a Mitochondrial ATP Synthase Subunit

Publisher: Elsevier BV

Date: 09-1994

DOI: 10.1006/ABBI.1994.1382

Abstract: A novel ATP synthase gene from soybean has been cloned and characterized. A subunit from the FA portion of the complex is encoded by two nuclear genes. The genomic clone(s) contain five exons encoding a protein of 179 amino acids. The amino terminal end contains many properties of a mitochondrial targeting sequence and preliminary in vitro import studies indicate that there is a cleavable precursor of approximately 30 amino acids. The predicted protein sequence shows high homology with the N-terminal sequence from an isolated subunit of ATP synthase complex from spinach (Hamsaur and Glaser (1992) Eur. J. Biochem. 205, 409-416). The subunit was tentatively identified as the equivalent of subunit d in bovine and P18 in yeast based on structural identity.

Glutamate transport by plant mitochondria

Publisher: Elsevier BV

Date: 05-1977

DOI: 10.1016/0304-4211(77)90007-4

Molecular Distinction between Alternative Oxidase from Monocots and Dicots

Publisher: Oxford University Press (OUP)

Date: 07-2002

DOI: 10.1104/PP.004150

Localization of H+ -ATPase in soybean root nodules

Publisher: Springer Science and Business Media LLC

Date: 19-07-1999

DOI: 10.1007/S004250050603

Abstract: The localization of H(+)-ATPases in soybean (Glycine max L. cv. Stevens) nodules was investigated using antibodies against both P-type and V-type enzymes. Immunoblots of peribacteroid membrane (PBM) proteins using antibodies against tobacco and Arabidopsis H(+)-ATPases detected a single immunoreactive band at approximately 100 kDa. These antibodies recognized a protein of similar relative molecular mass in the crude microsomal fraction from soybean nodules and uninoculated roots. The amount of this protein was greater in PBM from mature nodules than in younger nodules. Immunolocalization of P-type ATPases using silver enhancement of colloidal-gold labelling at the light-microscopy level showed signal distributed around the periphery of non-infected cells in both the nodule cortex and nodule parenchyma. In the central nitrogen-fixing zone of the nodule, staining was present in both the infected and uninfected cells. Examination of nodule sections using confocal microscopy and fluorescence staining showed an immunofluorescent signal clearly visible around the periphery of in idual symbiosomes which appeared as vesicles distributed throughout the infected cells of the central zone. Electron-microscopic examination of immunogold-labelled sections shows that P-type ATPase antigens were present on the PBM of both newly formed, single-bacteroid symbiosomes just released from infection threads, and on the PBM of mature symbiosomes containing two to four bacteroids. Immunogold labelling using antibody against the B-subunit of V-type ATPase from oat failed to detect this protein on symbiosome membranes. Only a very faint signal with this antibody was detected on Western blots of purified PBM. During nodule development, fusion of small symbiosomes to form larger ones containing multiple bacteroids was observed. Fusion was preceded by the formation of cone-like extensions of the PBM, allowing the membrane to make contact with the adjoining membrane of another symbiosome. We conclude that the major H(+)-ATPase on the PBM of soybean is a P-type enzyme with homology to other such enzymes in plants. In vivo, this enzyme is likely to play a critical role in the regulation of nutrient exchange between legume and bacteroids.

Transport of coenzyme A in plant mitochondria

Publisher: Elsevier BV

Date: 02-1984

DOI: 10.1016/0003-9861(84)90151-6

Abstract: Oxoglutarate oxidation by purified potato mitochondria which had been stored at low temperature for 48 h or longer was stimulated by added coenzyme A. Exogenous coenzyme A was accumulated by potato mitochondria, both freshly prepared and aged, in a manner sensitive to uncouplers and low temperature. Coenzyme A was concentrated approximately 10-fold in the matrix under steady-state conditions. This coenzyme A uptake followed saturation kinetics with an apparent Km of 0.2 mM and a V of 4-6.5 nmol min-1 mg-1 protein, suggesting carrier-mediated transport. This transport was insensitive to an inhibitor of NAD+ transport. It is suggested that plant mitochondria possess a specific carrier for the net accumulation of coenzyme A.

Transport of NAD⁺ in Percoll-Purified Potato Tuber Mitochondria

Publisher: Oxford University Press (OUP)

Date: 06-1985

DOI: 10.1104/PP.78.2.405

Environmental stress causes oxidative damage to plant mitochondria leading to inhibition of glycine decarboxylase

Publisher: Elsevier BV

Date: 11-2002

DOI: 10.1074/JBC.M204761200

Permeability of Isolated Infected Cells from Soybean Nodules

Publisher: Oxford University Press (OUP)

Date: 10-1991

DOI: 10.1093/JXB/42.10.1325

Respiratory gene expression in soybean cotyledons during post-germinative development

Publisher: Springer Science and Business Media LLC

Date: 2003

DOI: 10.1023/A:1022502501373

Abstract: Gene expression for nuclear- and mitochondrial-encoded subunits of respiratory chain components was measured in developing soybean cotyledons and compared to the abundance of the relevant proteins. Overall respiratory gene expression peaked at day 16, close to the peak in cytochrome chain and TCA cycle activities from day 10 to 15. Protein abundance followed transcript abundance for all components examined with the exception of the F1beta subunit of ATP synthase. A dramatic peak in F1beta transcript levels early in development (day 5 to 7) was not mirrored by an increase in protein suggesting translational or post-translational control. Mitochondrial-encoded transcripts were at least 10-fold more abundant than nuclear-encoded transcripts. The pattern of transcript and protein abundance for uncoupling proteins displayed a trend similar to other respiratory proteins examined, implicating similar control mechanisms. The expression of alternative oxidase differed, increasing throughout development with protein peaking at day 20, perhaps suggesting a role in senescence. Overall, this study indicated that respiratory gene expression and protein abundance is co-ordinated with respiratory activity for most components but that some components, such as the F1beta subunit may be under discrete forms of regulation.

Proteomic identification of divalent metal cation binding proteins in plant mitochondria

Publisher: Wiley

Date: 07-02-2003

DOI: 10.1016/S0014-5793(03)00101-7

Abstract: Divalent metal binding proteins in the Arabidopsis mitochondrial proteome were analysed by mobility shifts in the presence of alent cations during two-dimensional diagonal sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Tandem mass spectrometry and searches of the predicted Arabidopsis protein dataset were used in an attempt to identify 34 of the proteins which shifted. This analysis identified a total of 23 distinct protein spots as the products of at least 11 different Arabidopsis genes. A series of proteins known to be alent cation-binding proteins, or to catalyse alent cation-dependent reactions, were identified. These included: succinyl CoA ligase beta subunit, Mn-superoxide dismutase (SOD), an Fe-S centred component of complex I and the REISKE iron-sulphur protein of the b/c(1) complex. A further set of four proteins of known function but without known alent binding properties were also identified: the Vb subunit of cytochrome c oxidase, a subunit of ATP synthase (orfB), the acyl carrier protein, and the translocase of the outer membrane (TOM20). Three other proteins, of unknown function, were also found to shift in the presence of alent cations. This approach has broad application for the identification of sub-proteomes based on the metal interaction of polypeptides.

Isolation and properties of the outer membrane of plant mitochondria

Publisher: Elsevier BV

Date: 11-1975

DOI: 10.1016/0003-9861(75)90014-4

Abstract: URF13, an inner mitochondrial membrane protein of the maize Texas male-sterile cytoplasm (cms-T), has one orientation in the inner membrane of maize mitochondria but two topological orientations in the plasma membrane when expressed in Escherichia coli. Antibodies specific for the carboxyl terminus of URF13 and for an amino-terminal tag fused to URF13 in E. coli were used to determine the location of each end of the protein following protease treatments of right-side-out and inside-out vesicles derived from cms-T mitochondria and the E. coli plasma membrane. Cross-linking studies indicate that a portion of the URF13 population in mitochondria and E. coli exists in membranes in an oligomeric state and, in combination with proteolysis studies, show that in idual subunits within a given multimer have the same orientation. A three-membrane-spanning helical model for URF13 topology is presented.

Regulation of alternative oxidase activity in higher plants

Publisher: Springer Science and Business Media LLC

Date: 08-1995

DOI: 10.1007/BF02110000

Abstract: Implementing a lockdown or activity restriction to reduce the spread of COVID-19 cases is assumed to improve air quality in highly populated cities. The effect of lockdown on air quality is often quantified by comparing pre- and during-lockdown air quality parameters without considering confounding meteorological factors. We demonstrated that rainfall can explain changes in PM10 and PM2.5 parameters in the city of Jakarta during lockdown. This article shows that comparing air quality pre- and during lockdown is misleading. Variables affecting air quality such as meteorological variables should be taken into account. The air quality in Jakarta as measured by PM10 and PM2.5 did not change significantly during the lockdown period after removing the seasonal effect.

Divalent cation gating of an ammonium permeable channel in the symbiotic membrane from soybean nodules

Publisher: Wiley

Date: 11-1998

DOI: 10.1046/J.1365-313X.1998.00298.X

Lipoic Acid-Dependent Oxidative Catabolism of α-Keto Acids in Mitochondria Provides Evidence for Branched-Chain Amino Acid Catabolism in Arabidopsis

Publisher: Oxford University Press (OUP)

Date: 02-2004

DOI: 10.1104/PP.103.035675

Abstract: Lipoic acid-dependent pathways of α-keto acid oxidation by mitochondria were investigated in pea (Pisum sativum), rice (Oryza sativa), and Arabidopsis. Proteins containing covalently bound lipoic acid were identified on isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis separations of mitochondrial proteins by the use of antibodies raised to this cofactor. All these proteins were identified by tandem mass spectrometry. Lipoic acid-containing acyltransferases from pyruvate dehydrogenase complex and α-ketoglutarate dehydrogenase complex were identified from all three species. In addition, acyltransferases from the branched-chain dehydrogenase complex were identified in both Arabidopsis and rice mitochondria. The substrate-dependent reduction of NAD+ was analyzed by spectrophotometry using specific α-keto acids. Pyruvate- and α-ketoglutarate-dependent reactions were measured in all three species. Activity of the branched-chain dehydrogenase complex was only measurable in Arabidopsis mitochondria using substrates that represented the α-keto acids derived by deamination of branched-chain amino acids (Val [valine], leucine, and isoleucine). The rate of branched-chain amino acid- and α-keto acid-dependent oxygen consumption by intact Arabidopsis mitochondria was highest with Val and the Val-derived α-keto acid, α-ketoisovaleric acid. Sequencing of peptides derived from trypsination of Arabidopsis mitochondrial proteins revealed the presence of many of the enzymes required for the oxidation of all three branched-chain amino acids. The potential role of branched-chain amino acid catabolism as an oxidative phosphorylation energy source or as a detoxification pathway during plant stress is discussed.

Enzyme Distribution in Potato Mitochondria

Publisher: Oxford University Press (OUP)

Date: 1979

DOI: 10.1093/JXB/30.3.539

Tissue-Specific Expression of the Alternative Oxidase in Soybean and Siratro

Publisher: Oxford University Press (OUP)

Date: 06-1992

DOI: 10.1104/PP.99.2.712

Photosynthetic Performance and Fertility Are Repressed in GmAOX2b Antisense Soybean

Publisher: Oxford University Press (OUP)

Date: 22-01-2010

DOI: 10.1104/PP.109.149294

Abstract: The alternative oxidase (AOX) is a cyanide-resistant oxidase that provides an alternative outlet for electrons from the respiratory electron transport chain embedded in the inner membrane of plant mitochondria. Examination of soybean (Glycine max) plants carrying a GmAOX2b antisense gene showed AOX to have a central role in reproductive development and fecundity. In three independently transformed antisense lines, seed set was reduced by 16% to 43%, whereas ovule abortion increased by 1.2- to 1.7-fold when compared with nontransgenic transformation control plants. Reduced fecundity was associated with reductions in whole leaf cyanide-resistant, salicylhydroxamic acid-sensitive respiration and net photosynthesis, but there was no change in total respiration in the dark. The frequency of potential fertilization events was reduced by at least one-third in the antisense plants as a likely consequence of prefertilization defects. Pistils of the antisense plants contained a higher proportion of immature-sized, nonfertile embryo sacs compared with nontransgenic control plants. Increased rates of pollen abortion in vivo and reduced rates of pollen germination in vitro suggested that the antisense gene compromised pollen development and function. Reciprocal crosses between antisense and nontransgenic plants revealed that pollen produced by antisense plants was less active in fertilization. Taken together, the results presented here indicate that AOX expression has an important role in determining normal gametophyte development and function.

The soybean NRAMP homologue, GmDMT1, is a symbiotic divalent metal transporter capable of ferrous iron transport

Publisher: Wiley

Date: 08-07-2003

DOI: 10.1046/J.1365-313X.2003.01802.X

Abstract: Iron is an important nutrient in N2-fixing legume root nodules. Iron supplied to the nodule is used by the plant for the synthesis of leghemoglobin, while in the bacteroid fraction, it is used as an essential cofactor for the bacterial N2-fixing enzyme, nitrogenase, and iron-containing proteins of the electron transport chain. The supply of iron to the bacteroids requires initial transport across the plant-derived peribacteroid membrane, which physically separates bacteroids from the infected plant cell cytosol. In this study, we have identified Glycine max alent metal transporter 1 (GmDmt1), a soybean homologue of the NRAMP/Dmt1 family of alent metal ion transporters. GmDmt1 shows enhanced expression in soybean root nodules and is most highly expressed at the onset of nitrogen fixation in developing nodules. Antibodies raised against a partial fragment of GmDmt1 confirmed its presence on the peribacteroid membrane (PBM) of soybean root nodules. GmDmt1 was able to both rescue growth and enhance 55Fe(II) uptake in the ferrous iron transport deficient yeast strain (fet3fet4). The results indicate that GmDmt1 is a nodule-enhanced transporter capable of ferrous iron transport across the PBM of soybean root nodules. Its role in nodule iron homeostasis to support bacterial nitrogen fixation is discussed.

Differential impact of environmental stresses on the pea mitochondrial proteome

Publisher: Elsevier BV

Date: 08-2005

DOI: 10.1074/MCP.M400210-MCP200

Alterations in the Mitochondrial Alternative NAD(P)H Dehydrogenase NDB4 Lead to Changes in Mitochondrial Electron Transport Chain Composition, Plant Growth and Response to Oxidative Stress

Publisher: Oxford University Press (OUP)

Date: 09-06-2011

DOI: 10.1093/PCP/PCR073

Abstract: The branched respiratory electron transport chain of plants contains a non-phosphorylating alternative pathway consisting of type II NAD(P)H dehydrogenases on both sides of the inner membrane linked through the ubiquinone pool to an alternative oxidase (AOX). T-DNA and RNA interference (RNAi) were used to reduce gene expression to characterize the external NAD(P)H dehydrogenase NDB4 in Arabidopsis. The ndb4 lines showed different levels of suppression of NDB4 protein, leading to increases in NBD2 and AOX1a mRNA and protein levels in all lines. These changes were associated with lower reactive oxygen species formation and an altered phenotype, including changes in growth rate, root : shoot ratios and leaf area. The general growth pattern for the ndb4 mutants was decreased leaf area early in development (6-15 d) followed by a prompt subsequent increase in leaf area that exceeded the leaf area of the wild type by maturity (the 10-12 rosette stage). This pattern was most evident for the RNAi lines that had increased mitochondrial electron transport capacity. The RNAi lines also exhibited better tolerance to salinity stress, with better growth rates and lower shoot Na⁺ content compared with controls when grown under saline conditions. We hypothesize that these differences reflect the enhanced expression of NDB2 and AOX in the ndb4 mutant plants.

A tomato alternative oxidase protein with altered regulatory properties

Publisher: Elsevier BV

Date: 09-4220

DOI: 10.1016/S0005-2728(03)00112-9

Abstract: We have investigated the expression and regulatory properties of the two alternative oxidase (Aox) proteins that are expressed in tomato (Lycopersicon esculentum L. Mill cv. Sweetie) after storage of green fruit at 4 degrees C. Four Aox genes were identified in the tomato genome, of which two (LeAox1a and LeAox1b) were demonstrated to be expressed in cold-treated fruit. The activity and regulatory properties of LeAox1a and LeAox1b were assayed after expression of each protein in yeast cells (Saccharomyces cerevisiae), proving that each is an active Aox protein. The LeAox1b protein was shown to have altered regulatory properties due to the substitution of a Ser for the highly conserved Cys(I) residue. LeAox1b could not form inactive disulfide-linked dimers and was activated by succinate instead of pyruvate. This is the first ex le of a dicot species expressing a natural Cys(I)/Ser isoform. The implications of the existence and expression of such Aox isoforms is discussed in the light of the hypothesised role for Aox in plant metabolism.

Factors limiting respiration by isolated cauliflower mitochondria

Publisher: Elsevier BV

Date: 1977

DOI: 10.1016/0031-9422(77)84009-0

A critique of the use of inhibitors to estimate partitioning of electrons between mitochondrial respiratory pathways in plants

Publisher: Wiley

Date: 12-1995

DOI: 10.1034/J.1399-3054.1995.950404.X

Differential Expression of Alternative Oxidase Genes in Soybean Cotyledons during Postgerminative Development

Publisher: Oxford University Press (OUP)

Date: 10-1998

DOI: 10.1104/PP.118.2.675

Abstract: The expression of the alternative oxidase (AOX) was investigated during cotyledon development in soybean (Glycine max [L.] Merr.) seedlings. The total amount of AOX protein increased throughout development, not just in earlier stages as previously thought, and was correlated with the increase in capacity of the alternative pathway. Each AOX isoform (AOX1, AOX2, and AOX3) showed a different developmental trend in mRNA abundance, such that the increase in AOX protein and capacity appears to involve a shift in gene expression fromAOX2 to AOX3. As the cotyledons aged, the size of the mitochondrial ubiquinone pool decreased. We discuss how this and other factors may affect the alternative pathway activity that results from the developmental regulation of AOX expression.

Protein phosphorylation stimulates the rate of malate uptake across the peribacteroid membrane of soybean nodules

Publisher: Wiley

Date: 11-1991

DOI: 10.1016/0014-5793(91)81183-9

Abstract: Incubation of intact isolated symbiosomes with [gamma-32P]ATP, followed by isolation of the peribacteroid membrane and polypeptide analysis, showed that a single major polypeptide at 26 kDa was labelled. Antibodies raised against nodulin 26 reacted with a similar sized polypeptide. Incubation of the symbiosomes with alkaline phosphatase removed the label from this polypeptide. Pre-incubation with ATP stimulated malate accumulation by isolated symbiosomes, but only slightly (10-30%). Pre-treatment of symbiosomes with alkaline phosphatase inhibited malate uptake substantially and this inhibition was completely relieved by addition of ATP. The ATP stimulation of malate uptake was not affected by ATPase inhibitors. It is suggested that the rate of malate uptake across the peribacteroid membrane is controlled by phosphorylation of nodulin 26.

Hydroxamate-Stimulated O2 Uptake in Roots of Pisum sativum and Zea mays, Mediated by a Peroxidase

Publisher: Oxford University Press (OUP)

Date: 09-1986

DOI: 10.1104/PP.82.1.236

Organic acid activation of the alterNatlve oxidase of plant mitochondria

Publisher: Wiley

Date: 30-08-1993

DOI: 10.1016/0014-5793(93)80233-K

Abstract: Alternative oxidase activity (oxygen uptake in the presence of KCN, antimycin or myxothiazol) in mitochondria isolated from the roots of soybean seedlings was very slow, even with succinate as substrate. This activity was stimulated substantially (100-400%) by the addition of pyruvate, with half maximal stimulation occurring at 0.1 mM pyruvate. Mitochondria from soybean shoots displayed high alternative oxidase activity with succinate and malate as substrates but lower activity with exogenous NADH addition of pyruvate stimulated the activity with NADH up to that seen with succinate. This stimulation of cyanide-insensitive NADH oxidation was seen also with mitochondria from other species. Hydroxypyruvate and oxoglutarate could substitute for pyruvate, although higher concentrations were required to achieve maximum stimulation. Pyruvate stimulation of cyanide-insensitive oxygen uptake was observed with exogenous quinols as substrates, with sub-mitochondrial particles, and in the presence of the pyruvate transport inhibitor, cyanohydroxycinnamic acid, but was not observed with detergent-solubilised mitochondria. It is suggested that pyruvate acts allosterically on the alternative oxidase to stimulate its activity. The implications of these findings for respiration in vivo are discussed.

Investigations of the role of the main light-harvesting chlorophyll-protein complex in thylakoid membranes. Reconstitution of depleted membranes from intermittent-light-grown plants with the isolated

Publisher: Rockefeller University Press

Date: 1984

DOI: 10.1083/JCB.98.1.163

Abstract: The functions of the light-harvesting complex of photosystem II (LHC-II) have been studied using thylakoids from intermittent-light-grown (IML) plants, which are deficient in this complex. These chloroplasts have no grana stacks and only limited lamellar appression in situ. In vitro the thylakoids showed limited but significant Mg2+-induced membrane appression and a clear segregation of membrane particles into such regions. This observation, together with the immunological detection of small quantities of LHC-II apoproteins, suggests that the molecular mechanism of appression may be similar to the more extensive thylakoid stacking seen in normal chloroplasts and involve LHC-II polypeptides directly. To study LHC-II function directly, a sonication-freeze-thaw procedure was developed for controlled insertion of purified LHC-II into IML membranes. Incorporation was demonstrated by density gradient centrifugation, antibody agglutination tests, and freeze-fracture electron microscopy. The reconstituted membranes, unlike the parent IML membranes, exhibited both extensive membrane appression and increased room temperature fluorescence in the presence of cations, and a decreased photosystem I activity at low light intensity. These membranes thus mimic normal chloroplasts in this regard, suggesting that the incorporated LHC-II interacts with photosystem II centers in IML membranes and exerts a direct role in the regulation of excitation energy distribution between the two photosystems.

University Of Sydney

Location: Australia

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University Of Adelaide

Location: Australia

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Flinders University

Location: Australia

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Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0346892

Start Date: 03-2003

End Date: 06-2005

Amount: $689,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0230245

Start Date: 2001

End Date: 12-2002

Amount: $600,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0239218

Start Date: 2001

End Date: 12-2002

Amount: $340,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0560987

Start Date: 03-2005

End Date: 12-2005

Amount: $156,697.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0453722

Start Date: 2004

End Date: 12-2005

Amount: $385,240.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354751

Start Date: 2004

End Date: 12-2004

Amount: $10,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0775702

Start Date: 07-2008

End Date: 07-2008

Amount: $337,000.00

Funder: Australian Research Council

Industrial Transformation Research Hubs - Grant ID: IH140100013

Start Date: 06-2016

End Date: 12-2021

Amount: $3,972,614.00

Funder: Australian Research Council

Linkage - International - Grant ID: LX0560236

Start Date: 03-2005

End Date: 02-2006

Amount: $87,042.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0347922

Start Date: 2002

End Date: 12-2002

Amount: $630,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP140103090

Start Date: 2014

End Date: 12-2018

Amount: $387,095.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0561161

Start Date: 06-2005

End Date: 05-2006

Amount: $110,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0450577

Start Date: 2004

End Date: 06-2007

Amount: $450,000.00

Funder: Australian Research Council

Special Research Initiatives - Grant ID: SR0354715

Start Date: 2004

End Date: 12-2004

Amount: $40,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100010

Start Date: 12-2010

End Date: 12-2010

Amount: $720,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0772452

Start Date: 02-2007

End Date: 02-2010

Amount: $263,000.00

Funder: Australian Research Council