ORCID Profile
0000-0001-8070-3248
Current Organisation
University of Sydney
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Plant Physiology | Biochemistry And Cell Biology Not Elsewhere Classified | Biochemistry and Cell Biology | Global Change Biology | Plant Biology | Biochemistry and Cell Biology not elsewhere classified | Genetics | Plant Cell and Molecular Biology | Plant Physiology | Molecular Evolution | Biotechnology Not Elsewhere Classified | Macromolecular Design | Evolutionary Impacts of Climate Change | Gene Expression (incl. Microarray and other genome-wide approaches) | Genomics | Crop and Pasture Improvement (Selection and Breeding) | Bioinformatics
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Biological Sciences | Primary products from plants | Biological sciences | Integrated (ecosystem) assessment and management | Energy Conservation and Efficiency not elsewhere classified | Environmentally Sustainable Plant Production not elsewhere classified | Plant Production and Plant Primary Products not elsewhere classified | Solar-photoelectric | Energy Exploration not elsewhere classified | Energy transformation not elsewhere classified | Solar-Photovoltaic Energy | Environmentally Sustainable Energy Activities not elsewhere classified | Expanding Knowledge in the Environmental Sciences | Expanding Knowledge in the Chemical Sciences |
Related Links
Publications
The major light-harvesting pigment protein ofAcaryochloris marina
Publisher: Wiley
Date: 14-02-2002
DOI: 10.1016/S0014-5793(02)02315-3
Abstract: The major light-harvesting protein complex containing chlorophyll (Chl) d was isolated from Acaryochloris marina thylakoid membranes. Isolation was achieved by detergent solubilisation followed by separation on 6-40% sucrose gradients using ultracentrifugation. The best Chl d yield (70%) used 0.3% dodecyl maltoside, 0.15% octyl glucoside, 0.05% zwittergent 3-14 with the detergent:total Chl d ratio around 10:1 (w/w). Characterisation of the light-harvesting pigment protein complex (lhc) involved non-denaturing electrophoresis, SDS-PAGE, absorbance and fluorescence spectroscopy. The main polypeptide in the lhc was shown to be ca. 34 kDa and to contain Chl d and Chl a, indicating that the Acaryochloris lhc is similar to that of prochlorophytes. The Chl a level varied with the culture conditions, which is consistent with previous findings.
Photosynthesis | Chlorophylls
Publisher: Elsevier
Date: 2021
Chlorophylls d and f: Synthesis, occurrence, light-harvesting, and pigment organization in chlorophyll-binding protein complexes
Publisher: Elsevier
Date: 2019
Evolution of the Inner Light-Harvesting Antenna Protein Family of Cyanobacteria, Algae, and Plants
Publisher: Springer Science and Business Media LLC
Date: 02-2007
DOI: 10.1007/S00239-006-0058-2
Abstract: Two hypotheses account for the evolution of the inner antenna light-harvesting proteins of oxygenic photosynthesis in cyanobacteria, algae, and plants: one in which the CP43 protein of photosytem II gave rise to the extrinsic CP43-like antennas of cyanobacteria (i.e. IsiA and Pcb proteins), as a late development, and the other in which CP43 and CP43-like proteins derive from an ancestral protein. In order to determine which of these hypotheses is most likely, we analyzed the family of antenna proteins by a variety of phylogenetic techniques, using alignments of the six common membrane-spanning helices, constructed using information on the antenna proteins' three-dimensional structure, and surveyed for evidence of factors that might confound inference of a correct phylogeny. The first hypothesis was strongly supported. As a consequence, we conclude that the ancestral photosynthetic apparatus, with 11 membrane-spanning helices, split at an early stage during evolution to form, on the one hand, the reaction center of photosystem II and, on the other hand, the ancestor of inner antenna proteins, CP43 (PsbC) and CP47 (PsbB). Only much later in evolution did the CP43 lineage give rise to the CP43' proteins (IsiA and Pcb) of cyanobacteria.
Chromatic Acclimation Processes and Their Relationships with Phycobiliprotein Complexes
Publisher: MDPI AG
Date: 03-08-2022
DOI: 10.3390/MICROORGANISMS10081562
Abstract: Chromatic acclimation (CA) is a widespread mechanism for optimizing the composition of phycobiliprotein complexes to maximize the cyanobacterial light capture efficiency. There are seven CA types, CA1-CA7, classified according to various photoregulatory pathways. Here, we use sequence analyses and bioinformatics to predict the presence of CA types according to three GAF (cGMP phosphodiesterase/adenylyl cyclase/FhlA)-containing photoreceptors, CcaS (cyanobacterial chromatic acclimation sensor), RcaE (regulator of chromatic adaptation), and RfpA (regulator for far-red photoacclimation). These photoreceptors were classified into three different phylogenetic groups leading different CA types in a erse range of cyanobacteria. Combining with genomic information of phycobilisome compositions, the CA capabilities of various cyanobacteria were conjectured. Screening 65 accessible cyanobacterial genomes, we defined 19 cyanobacteria that have the capability to perform far-red light photoacclimation (FaRLiP) under the control of RfpA. Forty out of sixty-five cyanobacteria have the capability to perform green/red light photoacclimation, although they use different photoreceptors (RcaE and/or CcaS) and photoregulatory pathways. The reversible response of photoreceptors in CA regulation pathways trigged by changed light conditions reflects the flexibility of photoregulatory mechanisms in cyanobacteria and the putative independent evolutionary origin of photoacclimation types.
Modeling the Characteristic Residues of Chlorophyll f Synthase (ChlF) from Halomicronema hongdechloris to Determine Its Reaction Mechanism
Publisher: MDPI AG
Date: 13-09-2023
A unique photosystem I reaction center from a chlorophyll d‐containing cyanobacterium Acaryochloris marina
Publisher: Wiley
Date: 24-06-2021
DOI: 10.1111/JIPB.13113
Abstract: Photosystem I (PSI) is a large protein supercomplex that catalyzes the light‐dependent oxidation of plastocyanin (or cytochrome c 6 ) and the reduction of ferredoxin. This catalytic reaction is realized by a transmembrane electron transfer chain consisting of primary electron donor (a special chlorophyll (Chl) pair) and electron acceptors A 0 , A 1 , and three Fe 4 S 4 clusters, F X , F A , and F B . Here we report the PSI structure from a Chl d ‐dominated cyanobacterium Acaryochloris marina at 3.3 Å resolution obtained by single‐particle cryo‐electron microscopy. The A. marina PSI exists as a trimer with three identical monomers. Surprisingly, the structure reveals a unique composition of electron transfer chain in which the primary electron acceptor A 0 is composed of two pheophytin a rather than Chl a found in any other well‐known PSI structures. A novel subunit Psa27 is observed in the A. marina PSI structure. In addition, 77 Chls, 13 α‐carotenes, two phylloquinones, three Fe‐S clusters, two phosphatidyl glycerols, and one monogalactosyl‐diglyceride were identified in each PSI monomer. Our results provide a structural basis for deciphering the mechanism of photosynthesis in a PSI complex with Chl d as the dominating pigments and absorbing far‐red light.
Kovacikia minuta sp. nov. (Leptolyngbyaceae, Cyanobacteria), a new freshwater chlorophyll f‐producing cyanobacterium
Publisher: Wiley
Date: 18-04-2022
DOI: 10.1111/JPY.13248
Abstract: A few groups of cyanobacteria have been characterized as having far‐red light photoacclimation (FaRLiP) that results from chlorophyll f (Chl f ) production. In this study, using a polyphasic approach, we taxonomically transferred the Cf. Leptolyngbya sp. CCNUW1 isolated from a shaded freshwater pond, which produces Chl f under far‐red light, to the genus Kovacikia and named this taxon Kovacikia minuta sp. nov. This strain was morphologically similar to Leptolyngbya‐ like strains. The thin filaments were purplish‐brown under white light but became grass green under far‐red light. The 31‐gene phylogeny grouped K . minuta CCNU0001 into order Synechococcales and family Leptolyngbyaceae. Phylogenetic analysis based on 16S rRNA gene sequences further showed that K . minuta CCNU0001 was clustered into Kovacikia with similarities of 97.2–97.4% to the recently reported type species of Kovacikia muscicola HA7619‐LM3. Additionally, the internal transcribed spacer region between 16S–23S rRNA genes had a unique sequence and secondary structure compared with other Kovacikia strains and phylogenetically related taxa. Draft genome sequences of K . minuta CCNU0001 (8,564,336 bp) were assembled into one circular chromosome and two circular plasmids. A FaRLiP 20‐gene cluster comprised two operons with the unique organization. In sum, K . minuta was established as a new species, and it is the first species reported to produce Chl f and for which a draft genome was produced in genus Kovacikia . This study expanded our knowledge regarding the ersity of Chl f ‐producing cyanobacteria in far‐red light‐enriched environments and provides important foundational information for future investigations of FaRLiP evolution in cyanobacteria.
Expanding the solar spectrum used by photosynthesis
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.TPLANTS.2011.03.011
Abstract: A limiting factor for photosynthetic organisms is their light-harvesting efficiency, that is the efficiency of their conversion of light energy to chemical energy. Small modifications or variations of chlorophylls allow photosynthetic organisms to harvest sunlight at different wavelengths. Oxygenic photosynthetic organisms usually utilize only the visible portion of the solar spectrum. The cyanobacterium Acaryochloris marina carries out oxygenic photosynthesis but contains mostly chlorophyll d and only traces of chlorophyll a. Chlorophyll d provides a potential selective advantage because it enables Acaryochloris to use infrared light (700-750 nm) that is not absorbed by chlorophyll a. Recently, an even more red-shifted chlorophyll termed chlorophyll f has been reported. Here, we discuss using modified chlorophylls to extend the spectral region of light that drives photosynthetic organisms.
The Evolution of Far-Red Light Perception in Acaryochloris Marina, a Chlorophyll d-Containing Cyanobacterium
Publisher: Springer Berlin Heidelberg
Date: 2013
Structure of a large photosystem II supercomplex from Acaryochloris marina
Publisher: Wiley
Date: 26-01-2005
DOI: 10.1016/J.FEBSLET.2005.01.023
Abstract: Acaryochloris marina is a prochlorophyte-like cyanobacterium containing both phycobilins and chlorophyll d as light harvesting pigments. We show that the chlorophyll d light harvesting system, composed of Pcb proteins, functionally associates with the photosystem II (PSII) reaction center (RC) core to form a giant supercomplex. This supercomplex has a molecular mass of about 2300 kDa and dimensions of 385 A x 240 A. It is composed of two PSII-RC core dimers arranged end-to-end, flanked by eight symmetrically related Pcb proteins on each side. Thus each PSII-RC monomer has four Pcb subunits acting as a light harvesting system which increases the absorption cross section of the PSII-RC core by almost 200%.
Comparative analysis of thylakoid protein complexes in the mesophyll and bundle sheath cells from C3 , C4 and C3 -C4 Paniceae grasses.
Publisher: Wiley
Date: 23-04-2019
DOI: 10.1111/PPL.12956
Abstract: To better understand the coordination between dark and light reactions during the transition from C
18 O Labeling of Chlorophyll d in Acaryochloris marina Reveals That Chlorophyll a and Molecular Oxygen Are Precursors
Publisher: Elsevier BV
Date: 09-2010
Unique Origin and Lateral Transfer of Prokaryotic Chlorophyll-b and Chlorophyll-d Light-Harvesting Systems
Publisher: Oxford University Press (OUP)
Date: 08-09-2004
Extinction coefficient for red-shifted chlorophylls: Chlorophyll d and chlorophyll f
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.BBABIO.2012.02.026
Abstract: Both chlorophyll f and chlorophyll d are red-shifted chlorophylls in oxygenic photosynthetic organisms, which extend photon absorbance into the near infrared region. This expands the range of light that can be used to drive photosynthesis. Quantitative determination of chlorophylls is a crucial step in the investigation of chlorophyll-photosynthetic reactions in the field of photobiology and photochemistry. No methods have yet been worked out for the quantitative determination of chlorophyll f. There is also no method available for the precise quantitative determination of chlorophyll d although it was discovered in 1943. In order to obtain the extinction coefficients (ε) of chlorophyll f and chlorophyll d, the concentrations of chlorophylls were determined by Inductive Coupled Plasma Mass Spectrometry according to the fact that each chlorophyll molecule contains one magnesium (Mg) atom. Molar extinction coefficient ε(chl f) is 71.11×10(3)Lmol(-1)A(707nm)cm(-1) and ε(chl d) is 63.68×10(3)Lmol(-1)A(697nm)cm(-1) in 100% methanol. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.
The nature of the photosystem II reaction centre in the chlorophyll d-containing prokaryote, Acaryochloris marina
Publisher: Springer Science and Business Media LLC
Date: 12-2005
DOI: 10.1039/B507057K
Abstract: Pigment-protein complexes enriched in photosystem II (PS II) have been isolated from the chlorophyll (Chl) d containing cyanobacterium, Acaryochloris marina. A small PS II-enriched particle, we call 'crude reaction centre', contained 20 Chl d, 0.5 Chl a and 1 redox active cytochrome b-559 per 2 pheophytin a, plus the D1 and D2 proteins. A larger PS II-enriched particle, we call 'core', additionally bound the antenna complexes, CP47 and CP43, and had a higher chlorophyll per pheophytin ratio. Pheophytin a could be photoreduced in the presence of a strong reductant, indicating that it is the primary electron acceptor in photosystem II of A. marina. A substoichiometric amount of Chl a (less than one chlorophyll a per 2 pheophytin a) strongly suggests that Chl a does not have an essential role in the photochemistry of PS II in this organism. We conclude that PS II, in A. marina, utilizes Chl d and not Chl a as primary electron donor and that the primary electron acceptor is one of two molecules of pheophytin a.
A Novel Epiphytic Chlorophyll d‐containing Cyanobacterium Isolated from a Mangrove‐associated Red Alga
Publisher: Wiley
Date: 16-10-2012
DOI: 10.1111/J.1529-8817.2012.01233.X
Abstract: A new habitat and a new chlorophyll (Chl) d-containing cyanobacterium belonging to the genus Acaryochloris are reported in this study. Hyperspectral microscopy showed the presence of Chl d-containing microorganisms in epiphytic biofilms on a red alga (Gelidium caulacantheum) colonizing the pneumato-phores of a temperate mangrove (Avicennia marina). The presence of Chl d was further proven by high performance liquid chromatography (HPLC)-based pigment analysis and by confocal imaging of cultured cells. Enrichment of mangrove biofilm s les under near-infrared radiation (NIR) yielded the new Acaryochloris sp. MPGRS1, which was closely related in terms of 16S rRNA gene sequence to an isolate from the hypertrophic Salton Sea, USA. The new isolate used Chl d as its major photopigment Chl d and Chl a contents were ~98% and 1%-2% of total cellular chlorophyll, respectively. These findings expand the variety of ecological niches known to harbor Chl d-containing cyanobacteria and support our working hypothesis that such oxyphototrophs may be ubiquitous in habitats depleted of visible light, but with sufficient NIR exposure.
Genome and proteome of the chlorophyll f-producing cyanobacterium Halomicronema hongdechloris: adaptative proteomic shifts under different light conditions.
Publisher: Springer Science and Business Media LLC
Date: 12-03-2019
Iron deficiency induces a chlorophyll d-binding Pcb antenna system around Photosystem I in Acaryochloris marina
Publisher: Elsevier BV
Date: 07-2005
DOI: 10.1016/J.BBABIO.2005.05.007
Abstract: The prochlorophyte-like cyanobacterium Acaryochloris marina contains two pcb genes, pcbA and pcbC, which encode chlorophyll (Chl) d-binding antenna proteins PcbA and PcbC, respectively. Using real-time reverse transcriptase polymerase chain reaction (RT-PCR), it is shown that when Acaryochloris cells are grown in an iron-deficient medium, the transcription of the pcbC gene is up-regulated compared to that of pcbA. Biochemical and immunological analyses indicated that under the same iron-deficient conditions, the level of Photosystem I (PSI) decreased compared with that of Photosystem II (PSII). Electron microscopy revealed that concomitant with these changes was the formation of Pcb-PSI supercomplexes which, in their largest form, were composed of 18 Pcb subunits forming a ring around the trimeric PSI reaction centre core. Mass spectrometry indicated that the PcbC protein is the main constituent of this outer PSI antenna system. It is therefore concluded that in Acaryochloris, the PcbC protein forms an antenna for PSI when iron levels become limiting and in this way compensates for the drop in the level of PSI relative to PSII which occurs under these conditions.
Functional specialization of expanded orange carotenoid protein paralogs in subaerial Nostoc species
Publisher: Oxford University Press (OUP)
Date: 18-04-2023
Abstract: Orange carotenoid protein (OCP) is a photoactive protein that participates in the photoprotection of cyanobacteria. There are 2 full-length OCP proteins, 4 N-terminal paralogs (helical carotenoid protein [HCP]), and 1 C-terminal domain-like carotenoid protein (CCP) found in Nostoc flagelliforme, a desert cyanobacterium. All HCPs (HCP1 to 3 and HCP6) from N. flagelliforme demonstrated their excellent singlet oxygen quenching activities, in which HCP2 was the strongest singlet oxygen quencher compared with others. Two OCPs, OCPx1 and OCPx2, were not involved in singlet oxygen scavenging instead, they functioned as phycobilisome fluorescence quenchers. The fast-acting OCPx1 showed more effective photoactivation and stronger phycobilisome fluorescence quenching compared with OCPx2, which behaved differently from all reported OCP paralogs. The resolved crystal structure and mutant analysis revealed that Trp111 and Met125 play essential roles in OCPx2, which is dominant and long acting. The resolved crystal structure of OCPx2 is maintained in a monomer state and showed more flexible regulation in energy quenching activities compared with the packed oligomer of OCPx1. The recombinant apo-CCP obtained the carotenoid pigment from holo-HCPs and holo-OCPx1 of N. flagelliforme. No such carotenoid transferring processes were observed between apo-CCP and holo-OCPx2. The close phylogenetic relationship of OCP paralogs from subaerial Nostoc species indicates an adaptive evolution toward development of photoprotection: protecting cellular metabolism against singlet oxygen damage using HCPs and against excess energy captured by active phycobilisomes using 2 different working modes of OCPx.
Light Harvesting Modulation in Photosynthetic Organisms
Publisher: Springer International Publishing
Date: 2021
Chlorophylldas the major photopigment inAcaryochloris marina
Publisher: World Scientific Pub Co Pte Ltd
Date: 12-2002
DOI: 10.1142/S1088424602000889
Abstract: Chlorophyll (Chl) d is the major pigment in the photosystems (PS) and light-harvesting complex(es) of Acaryochloris marina. Chl a is present in small and variable amounts in PSII and in the light-harvesting complex(es). Isolated PSII complex showed a major fluorescence emission peak at 725 nm and a smaller emission peak due to Chl d at 701 nm, while the PSI complex showed two pools of Chl d, one with emission at 730 nm and the other at 709 nm at 77 K. In PSI and PSII of classical cyanobacteria and of higher plants, where Chl a is the predominant pigment rather than Chl d, these differences are not as pronounced. Light energy absorbed by phycobiliproteins was also active in these Chl d emissions. The major light-harvesting pigment protein is similar to the prochlorophyte Chl-binding protein (pcb) and had a major emission peak at 711 nm. In Cyanobacteria an iron-stress induced Chl-binding protein (isiA) forms a polymeric ring around PSI, and so the effect(s) of iron stress on A. marina where investigated. No clear evidence could be deduced for the formation of an isiA protein under iron stress and no clear changes in the proportion of Chl d :Chl a could be discerned although phycobilins showed a decreased under iron-stress conditions. That Chl d replaces Chl a in all its functions in A. marina is clear the advantage of this evolutionary development appears to be to enable A. marina to absorb far-red light which occurs in environments where red light is filtered out by other photosynthetic organisms.
Examination of the Photophysical Processes of Chlorophyll d Leading to a Clarification of Proposed Uphill Energy Transfer Processes in Cells of Acaryochloris marina¶
Publisher: American Society for Photobiology
Date: 05-2007
Biogeography of Photosynthetic Light-Harvesting Genes in Marine Phytoplankton
Publisher: Public Library of Science (PLoS)
Date: 25-02-2009
Chlorophyll d and Acaryochloris marina: current status
Publisher: Springer Science and Business Media LLC
Date: 25-04-2013
DOI: 10.1007/S11120-013-9829-Y
Abstract: The discovery of the chlorophyll d-containing cyanobacterium Acaryochloris marina in 1996 precipitated a shift in our understanding of oxygenic photosynthesis. The presence of the red-shifted chlorophyll d in the reaction centre of the photosystems of Acaryochloris has opened up new avenues of research on photosystem energetics and challenged the unique status of chlorophyll a in oxygenic photosynthesis. In this review, we detail the chemistry and role of chlorophyll d in photosynthesis and summarise the unique adaptations that have allowed the proliferation of Acaryochloris in erse ecological niches around the world.
Chromatic photoacclimation extends utilisable photosynthetically active radiation in the chlorophyll d-containing cyanobacterium, Acaryochloris marina
Publisher: Springer Science and Business Media LLC
Date: 07-2009
DOI: 10.1007/S11120-009-9466-7
Abstract: Chromatic photoacclimation and photosynthesis were examined in two strains of Acaryochloris marina (MBIC11017 and CCMEE5410) and in Synechococcus PCC7942. Acaryochloris contains Chl d, which has an absorption peak at ca 710 nm in vivo. Cultures were grown in one of the three wavelengths (525 nm, 625 nm and 720 nm) of light from narrow-band photodiodes to determine the effects on pigment composition, growth rate and photosynthesis: no growth occurred in 525 nm light. Synechococcus did not grow in 720 nm light because Chl a does not absorb effectively at this long wavelength. Acaryochloris did grow in 720 nm light, although strain MBIC11017 showed a decrease in phycobilins over time. Both Synechococcus and Acaryochloris MBIC11017 showed a dramatic increase in phycobilin content when grown in 625 nm light. Acaryochloris CCMEE5410, which lacks phycobilins, would not grow satisfactorily under 625 nm light. The cells adjusted their pigment composition in response to the light spectral conditions under which they were grown. Photoacclimation and the Q (y) peak of Chl d could be understood in terms of the ecological niche of Acaryochloris, i.e. habitats enriched in near infrared radiation.
Orange and red carotenoid proteins are involved in the adaptation of the terrestrial cyanobacterium Nostoc flagelliforme to desiccation
Publisher: Springer Science and Business Media LLC
Date: 02-03-2019
DOI: 10.1007/S11120-019-00629-6
Abstract: The remarkable drought-resistance of the terrestrial cyanobacterium Nostoc flagelliforme (N. flagelliforme) has attracted attention for many years. In this study, we purified a group of red proteins that accumulate in dried field s les of N. flagelliforme. These red proteins contain canthaxanthin as the bound chromophore. Native-PAGE analysis revealed that the purified red proteins resolved into six visible red bands and were composed of four helical carotenoid proteins (HCPs), HCP1, HCP2, HCP3, and HCP6 (homologs to the N-terminal domain of the orange carotenoid protein (OCP)). Seven genes encode homologs of the OCP in the genome of N. flagelliforme: two full-length ocp genes (ocpx1 and ocpx2), four N-terminal domain hcp genes (hcp1, hcp2, hcp3, and hcp6), and one C-terminal domain ccp gene. The expression levels of hcp1, hcp2, and hcp6 were highly dependent on the water status of field N. flagelliforme s les, being downregulated during rehydration and upregulated during subsequent dehydration. Transcripts of ocpx2 were dominant in the dried field s les, which we confirmed by detecting the presence of OCPx2-derived peptides in the purified red proteins. The results shed light on the relationship between carotenoid-binding proteins and the desiccation resistance of terrestrial cyanobacteria, and the physiological functions of carotenoid-binding protein complexes in relation to desiccation are discussed.
Structure of a photosystem II supercomplex isolated from Prochloron didemni retaining its chlorophyll a/b light-harvesting system
Publisher: Proceedings of the National Academy of Sciences
Date: 07-2003
Abstract: Prochlorophytes are a class of cyanobacteria that do not use phycobiliproteins as light-harvesting systems, but contain chlorophyll (Chl) a / b -binding Pcb proteins. Recently it was shown that Pcb proteins form an 18-subunit light-harvesting antenna ring around the photosystem I (PSI) trimeric reaction center complex of the prochlorophyte Prochlorococcus marinus SS120. Here we have investigated whether the symbiotic prochlorophyte Prochloron didemni also contains the same supermolecular complex. Using cells isolated directly from its ascidian host, we found no evidence for the presence of the Pcb–PSI supercomplex. Instead we have identified and characterized a supercomplex composed of photosystem II (PSII) and Pcb proteins. We show that 10-Pcb subunits associate with the PSII dimeric reaction center core to form a giant complex having an estimated M r of 1,500 kDa with dimensions of 210 × 290 Å. Five-Pcb subunits flank each long side of the dimer and assuming each binds 13 Chl molecules, increase the antenna size of PSII by ≈200%. Fluorescence emission studies indicate that energy transfer occurs efficiently from the Pcb antenna. Modeling using the x-ray structure of cyanobacterial PSII suggests that energy transfer to the PSII reaction center is via the Chls bound to the CP47 and CP43 proteins.
Spectroscopic Studies of Photosystem II in Chlorophyll d-Containing Acaryochloris marina
Publisher: American Chemical Society (ACS)
Date: 26-07-2005
DOI: 10.1021/BI048314C
Subcellular pigment distribution is altered under far-red light acclimation in cyanobacteria that contain chlorophyll f
Publisher: Springer Science and Business Media LLC
Date: 11-09-2017
DOI: 10.1007/S11120-017-0428-1
Abstract: Far-Red Light (FRL) acclimation is a process that has been observed in cyanobacteria and algae that can grow solely on light above 700 nm. The acclimation to FRL results in rearrangement and synthesis of new pigments and pigment-protein complexes. In this study, cyanobacteria containing chlorophyll f, Synechococcus sp. PCC 7335 and Halomicronema hongdechloris, were imaged as live cells with confocal microscopy. H. hongdechloris was further studied with hyperspectral confocal fluorescence microscopy (HCFM) and freeze-substituted thin-section transmission electron microscopy (TEM). Under FRL, phycocyanin-containing complexes and chlorophyll-containing complexes were determined to be physically separated and the synthesis of red-form phycobilisome and Chl f was increased. The timing of these responses was observed. The heterogeneity and eco-physiological response of the cells was noted. Additionally, a gliding motility for H. hongdechloris is reported.
Correlation of bio-optical properties with photosynthetic pigment and microorganism distribution in microbial mats from Hamelin Pool, Australia
Publisher: Oxford University Press (OUP)
Date: 31-10-2018
Abstract: Microbial mats and stromatolites are widespread in Hamelin Pool, Shark Bay, however the phototrophic capacity of these systems is unknown. This study has determined the optical properties and light-harvesting potential of these mats with light microsensors. These characteristics were linked via a combination of 16S rDNA sequencing, pigment analyses and hyperspectral imaging. Local scalar irradiance was elevated over the incident downwelling irradiance by 1.5-fold, suggesting light trapping and strong scattering by the mats. Visible light (400-700 nm) penetrated to a depth of 2 mm, whereas near-infrared light (700-800 nm) penetrated to at least 6 mm. Chlorophyll a and bacteriochlorophyll a (Bchl a) were found to be the dominant photosynthetic pigments present, with BChl a peaking at the subsurface (2-4 mm). Detailed 16S rDNA analyses revealed the presence of putative Chl f-containing Halomicronema sp. and photosynthetic members primarily decreased from the mat surface down to a depth of 6 mm. Data indicated high abundances of some pigments and phototrophic organisms in deeper layers of the mats (6-16 mm). It is proposed that the photosynthetic bacteria present in this system undergo unique adaptations to lower light conditions below the mat surface, and that phototrophic metabolisms are major contributors to ecosystem function.
Optimization and effects of different culture conditions on growth of Halomicronema hongdechloris – a filamentous cyanobacterium containing chlorophyll f
Publisher: Frontiers Media SA
Date: 2014
Photosynthesis | Photosynthesis
Publisher: Elsevier
Date: 2021
Biology of the Chlorophyll D-Containing Cyanobacterium Acaryochloris Marina
Publisher: Springer Netherlands
Date: 2007
An electron paramagnetic resonance investigation of the electron transfer reactions in the chlorophyll d containing photosystem I of Acaryochloris marina
Publisher: Wiley
Date: 15-03-2007
DOI: 10.1016/J.FEBSLET.2007.03.014
Abstract: Electron paramagnetic resonance (EPR) spectroscopy reveals functional and structural similarities between the reaction centres of the chlorophyll d-binding photosystem I (PS I) and chlorophyll a-binding PS I. Continuous wave EPR spectrometry at 12K identifies iron-sulphur centres as terminal electron acceptors of chlorophyll d-binding PS I. A transient light-induced electron spin echo (ESE) signal indicates the presence of a quinone as the secondary electron acceptor (Q) between P(740)(+) and the iron-sulphur centres. The distance between P(740)(+) and Q(-) was estimated within point-dipole approximation as 25.23+/-0.05A, by the analysis of the electron spin echo envelope modulation.
Photosynthesis supported by a chlorophyll f-dependent, entropy-driven uphill energy transfer in Halomicronema hongdechloris cells adapted to far-red light
Publisher: Springer Science and Business Media LLC
Date: 23-07-2018
DOI: 10.1007/S11120-018-0556-2
Abstract: The phototrophic cyanobacterium Halomicronema hongdechloris shows far-red light-induced accumulation of chlorophyll (Chl) f, but the involvement of the pigment in photosynthetic energy harvesting by photosystem (PS) II is controversially discussed. While H. hongdechloris contains negligible amounts of Chl f in white-light culture conditions, the ratio of Chl f to Chl a is reversibly changed up to 1:8 under illumination with far-red light (720-730 nm). We performed UV-Vis absorption spectroscopy, time-integrated and time-resolved fluorescence spectroscopy for the calculation of decay-associated spectra (DAS) to determine excitation energy transfer (EET) processes between photosynthetic pigments in intact H. hongdechloris filaments. In cells grown under white light, highly efficient EET occurs from phycobilisomes (PBSs) to Chl a with an apparent time constant of about 100 ps. Charge separation occurs with a typical apparent time constant of 200-300 ps from Chl a. After 3-4 days of growth under far-red light, robust Chl f content was observed in H. hongdechloris and EET from PBSs reached Chl f efficiently within 200 ps. It is proposed based on mathematical modeling by rate equation systems for EET between the PBSs and PSII and subsequent electron transfer (ET) that charge separation occurs from Chl a and excitation energy is funneled from Chl f to Chl a via an energetically uphill EET driven by entropy, which is effective because the number of Chl a molecules coupled to Chl f is at least eight- to tenfold larger than the corresponding number of Chl f molecules. The long lifetime of Chl f molecules in contact to a tenfold larger pool of Chl a molecules allows Chl f to act as an intermediate energy storage level, from which the Gibbs free energy difference between Chl f and Chl a can be overcome by taking advantage from the favorable ratio of degeneracy coefficients, which formally represents a significant entropy gain in the Eyring formulation of the Arrhenius law. Direct evidence for energetically uphill EET and charge separation in PSII upon excitation of Chl f via anti-Stokes fluorescence in far-red light-adapted H. hongdechloris cells was obtained: Excitation by 720 nm laser light resulted in robust Chl a fluorescence at 680 nm that was distinctly temperature-dependent and, notably, increased upon DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) treatment in far-red light-adapted cells. Thus, rather than serving as an excitation energy trap, Chl f in far-red light-adapted H. hongdechloris cells is directly contributing to oxygenic photosynthesis at PSII.
Characterization of the sulfur-formation (suf) genes in Synechocystis sp. PCC 6803 under photoautotrophic and heterotrophic growth conditions
Publisher: Springer Science and Business Media LLC
Date: 14-07-2017
DOI: 10.1007/S00425-017-2738-0
Abstract: The sulfur-formation ( suf ) genes play important roles in both photosynthesis and respiration of cyanobacteria, but the organism prioritizes Fe-S clusters for respiration at the expense of photosynthesis. Iron-sulfur (Fe-S) clusters are important to all living organisms, but their assembly mechanism is poorly understood in photosynthetic organisms. Unlike non-photosynthetic bacteria that rely on the iron-sulfur cluster system, Synechocystis sp. PCC 6803 uses the Sulfur-Formation (SUF) system as its major Fe-S cluster assembly pathway. The co-expression of suf genes and the direct interactions among SUF subunits indicate that Fe-S assembly is a complex process in which no suf genes can be knocked out completely. In this study, we developed a condition-controlled SUF Knockdown mutant by inserting the petE promoter, which is regulated by Cu
UV‐B induced biosynthesis of a novel sunscreen compound in solar radiation and desiccation tolerant cyanobacteria
Publisher: Wiley
Date: 15-12-2017
Abstract: The small‐molecule sunscreen compounds, mycosporine‐like amino acids (MAAs), have strong ultraviolet (UV) absorption and can protect cyanobacteria against UV‐B damage. However, the molecular mechanism underlying UV‐B signaling and MAA chemical ersity remain largely unclear. Here, we identified a five‐gene cluster for MAA biosynthesis in the solar radiation and desiccation tolerant cyanobacterium Nostoc flagelliforme . A LuxR family protein OrrA was identified as a positive UV‐B responsive regulator binding to the promoter region of this gene cluster. OrrA functions as an activator mediating the UV‐B induced MAA biosynthesis. Overexpression of orrA strengthened its UV‐B tolerance during desiccation, and enhanced the photosynthetic recovery upon rehydration. Heterologous expression of this gene cluster in Anabaena PCC 7120 produces the same MAA as that in field s les of N . flagelliforme . The MAA structure is assigned as mycosporine‐2‐(4‐deoxygadusolyl‐ornithine) with a molecular weight of 756 Da, the structurally unique MAA compound reported to date. This MAA was catalyzed by mysD‐mysC2‐mysC1 encoding proteins from 4‐deoxygadusol, which was synthesized through the catalysis of mysA‐mysB products. Thus, we elucidated the transcriptional mechanism for a novel type MAA biosynthesis in solar radiation and desiccation tolerant cyanobacteria, which shed light on the identification of other components for UV‐B signaling in cyanobacteria.
Chapter 15 The Chemistry and Biology of Light-Harvesting Complex II and Thylakoid Biogenesis: raison d’etre of Chlorophylls b and c
Publisher: Springer Netherlands
Date: 2010
Structure of Chlorophyll f
Publisher: American Chemical Society (ACS)
Date: 15-03-2013
DOI: 10.1021/OL400327J
Abstract: Chlorophyll f (1) is the most red-shifted absorbing natural chlorophyll reported, and it is assigned the structure [2-formyl]-chlorophyll a (C55H70O6N4Mg). This structural assignment is confirmed based on the relative retention time on HPLC, mass spectroscopy, UV/vis absorption, and CD spectroscopy, and proton and carbon NMR of chlorophyll f purified from Halomicronema hongdechloris.
Characterization of isolated photosystem I from Halomicronema hongdechloris, a chlorophyll f-producing cyanobacterium
Publisher: Institute of Experimental Botany
Date: 03-2018
Genome Sequence of Rhodoferax antarcticus ANT.BRT; A Psychrophilic Purple Nonsulfur Bacterium from an Antarctic Microbial Mat
Publisher: MDPI AG
Date: 21-02-2017
Chlorophylls, ligands and assembly of light-harvesting complexes in chloroplasts
Publisher: Springer Science and Business Media LLC
Date: 16-05-2007
Novel chlorophylls and new directions in photosynthesis research
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/FP14350
Abstract: Chlorophyll d and chlorophyll f are red-shifted chlorophylls, because their Qy absorption bands are significantly red-shifted compared with chlorophyll a. The red-shifted chlorophylls broaden the light absorption region further into far red light. The presence of red-shifted chlorophylls in photosynthetic systems has opened up new possibilities of research on photosystem energetics and challenged the unique status of chlorophyll a in oxygenic photosynthesis. In this review, we report on the chemistry and function of red-shifted chlorophylls in photosynthesis and summarise the unique adaptations that have allowed the proliferation of chlorophyll d- and chlorophyll f-containing organisms in erse ecological niches around the world.
The identification of IsiA proteins binding chlorophyll d in the cyanobacterium Acaryochloris marina
Publisher: Springer Science and Business Media LLC
Date: 04-04-2017
DOI: 10.1007/S11120-017-0379-6
Abstract: The bioavailable iron in many aquatic ecosystems is extremely low, and limits the growth and photosynthetic activity of phytoplankton. In response to iron limitation, a group of chlorophyll-binding proteins known as iron stress-induced proteins are induced and serve as accessory light-harvesting components for photosystems under iron limitation. In the present study, we investigated physiological features of Acaryochloris marina in response to iron-deficient conditions. The growth doubling time under iron-deficient conditions was prolonged to ~3.4 days compared with 1.9 days under normal culture conditions, accompanied with dramatically decreased chlorophyll content. The isolation of chlorophyll-binding protein complexes using sucrose density gradient centrifugation shows six main green bands and three main fluorescence components of 712, 728, and 748 nm from the iron-deficient culture. The fluorescence components of 712 and 728 nm co-exist in the s les collected from iron-deficient and iron-replete cultures and are attributed to Chl d-binding accessory chlorophyll-binding antenna proteins and also from photosystem II. A new chlorophyll-binding protein complex with its main fluorescence peak at 748 nm was observed and enriched in the heaviest fraction from the s les collected from the iron-deficient culture only. Combining western blotting analysis using antibodies of CP47 (PSII), PsaC (PSI) and IsiA and proteomic analysis on an excised protein band at ~37 kDa, the heaviest fraction (-F6) isolated from iron-deficient culture contained Chl d-bound PSI-IsiA supercomplexes. The PSII-antenna supercomplexes isolated from iron-replete conditions showed two fluorescence peaks of 712 and 728 nm, which can be assigned as 6-transmembrane helix chlorophyll-binding antenna and photosystem II fluorescence, respectively, which is supported by protein analysis of the fractions (F5 and F6).
Chlorophyll f production in two new subaerial cyanobacteria of the family Oculatellaceae
Publisher: Wiley
Date: 09-03-2023
DOI: 10.1111/JPY.13314
Abstract: Chlorophyll (Chl) f was recently identified in a few cyanobacteria as the fifth chlorophyll of oxygenic organisms. In this study, two Leptolyngbya‐ like strains of CCNU0012 and CCNU0013 were isolated from a dry ditch in Chongqing city and a brick wall in Mount Emei Scenic Area in China, respectively. These two strains were described as new species: Elainella chongqingensis sp. nov. (Oculatellaceae, Synechococcales) and Pegethrix sichuanica sp. nov. (Oculatellaceae, Synechococcales) by the polyphasic approach based on morphological features, phylogenetic analysis of 16S rRNA gene and secondary structure comparison of 16S‐23S internal transcribed spacer domains. Both strains produced Chl a under white light (WL) but additionally induced Chl f synthesis under far‐red light (FRL). Unexpectedly, the content of Chl f in P. sichuanica was nearly half that in most Chl f ‐producing cyanobacteria. Red‐shifted phycobiliproteins were also induced in both strains under FRL conditions. Subsequently, additional absorption peak beyond 700 nm in the FRL spectral region appeared in these two strains. This is the first report of Chl f production induced by FRL in the family Oculatellaceae. This study not only extended the ersity of Chl f‐ producing cyanobacteria but also provided precious s les to elucidate the essential binding sites of Chl f within cyanobacterial photosystems.
Structural basis for the adaptation and function of chlorophyll f in photosystem I
Publisher: Springer Science and Business Media LLC
Date: 13-01-2020
DOI: 10.1038/S41467-019-13898-5
Abstract: Chlorophylls (Chl) play pivotal roles in energy capture, transfer and charge separation in photosynthesis. Among Chls functioning in oxygenic photosynthesis, Chl f is the most red-shifted type first found in a cyanobacterium Halomicronema hongdechloris . The location and function of Chl f in photosystems are not clear. Here we analyzed the high-resolution structures of photosystem I (PSI) core from H. hongdechloris grown under white or far-red light by cryo-electron microscopy. The structure showed that, far-red PSI binds 83 Chl a and 7 Chl f , and Chl f are associated at the periphery of PSI but not in the electron transfer chain. The appearance of Chl f is well correlated with the expression of PSI genes induced under far-red light. These results indicate that Chl f functions to harvest the far-red light and enhance uphill energy transfer, and changes in the gene sequences are essential for the binding of Chl f .
Characterization of red-shifted phycobilisomes isolated from the chlorophyll f-containing cyanobacterium Halomicronema hongdechloris
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.BBABIO.2015.10.009
Abstract: Phycobilisomes are the main light-harvesting protein complexes in cyanobacteria and some algae. It is commonly accepted that these complexes only absorb green and orange light, complementing chlorophyll absorbance. Here, we present a new phycobilisome derived complex that consists only of allophycocyanin core subunits, having red-shifted absorption peaks of 653 and 712 nm. These red-shifted phycobiliprotein complexes were isolated from the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, grown under monochromatic 730 nm-wavelength (far-red) light. The 3D model obtained from single particle analysis reveals a double disk assembly of 120-145 Å with two α/β allophycocyanin trimers fitting into the two separated disks. They are significantly smaller than typical phycobilisomes formed from allophycocyanin subunits and core-membrane linker proteins, which fit well with a reduced distance between thylakoid membranes observed from cells grown under far-red light. Spectral analysis of the dissociated and denatured phycobiliprotein complexes grown under both these light conditions shows that the same bilin chromophore, phycocyanobilin, is exclusively used. Our findings show that red-shifted phycobilisomes are required for assisting efficient far-red light harvesting. Their discovery provides new insights into the molecular mechanisms of light harvesting under extreme conditions for photosynthesis, as well as the strategies involved in flexible chromatic acclimation to erse light conditions.
Isolation of Complete Chloroplasts from Chromera Velia — the Photosynthetic Relative of Parasitic Apicomplexa
Publisher: Springer Berlin Heidelberg
Date: 2013
Energy transfer processes in chlorophyll f-containing cyanobacteria using time-resolved fluorescence spectroscopy on intact cells
Publisher: Elsevier BV
Date: 09-2014
DOI: 10.1016/J.BBABIO.2014.04.009
Abstract: We examined energy transfer dynamics in the unique chlorophyll (Chl) f-containing cyanobacterium Halomicronema hongdechloris. The absorption band of Chl f appeared during cultivation of this organism under far-red light. The absorption maximum of Chl f in organic solvents occurs at a wavelength of approximately 40 nm longer than that of Chl a. In vivo, the cells display a new absorption band at approximately 730 nm at 298 K, which is at a significantly longer wavelength than that of Chl a. We primarily assigned this band to a long wavelength form of Chl a. The function of Chl f is currently unknown. We measured the fluorescence of cells using time-resolved fluorescence spectroscopy in the picosecond-to-nanosecond time range and found clear differences in fluorescence properties between the cells that contained Chl f and the cells that did not. After excitation, the fluorescence peaks of photosystem I and photosystem II appeared quickly but diminished immediately. A unique fluorescence peak located at 748 nm subsequently appeared in cells containing Chl f. This finding strongly suggests that the Chl f in this alga exists in photosystem I and II complexes and is located close to each molecule of Chl a. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.
Supramolecular organization of phycobiliproteins in the chlorophylld-containing cyanobacteriumAcaryochloris marina
Publisher: Wiley
Date: 11-07-2009
DOI: 10.1016/J.FEBSLET.2009.07.012
Abstract: Here we report the high-resolution detail of the organization of phycobiliprotein structures associated with photosynthetic membranes of the chlorophyll d-containing cyanobacterium Acaryochloris marina. Cryo-electron transmission-microscopy on native cell sections show extensive patches of near-crystalline phycobiliprotein rods that are associated with the stromal side of photosynthetic membranes. This supramolecular photosynthetic structure represents a novel mechanism of organizing the photosynthetic light-harvesting machinery. In addition, the specific location of phycobiliprotein patches suggests a physical separation of photosystem I and photosystem II reaction centres. Based on this finding and the known photosystem's structure in Acaryochloris, we discuss possible membrane arrangements of photosynthetic membrane complexes in this species.
Far-red light promotes biofilm formation in the cyanobacterium Acaryochloris marina.
Publisher: Wiley
Date: 10-11-2017
Abstract: Light quantity and quality promotes ecological-niche differentiation of photosynthetic organisms. The existence of cyanobacteria capable of performing photosynthesis using red-shifted chlorophylls, chlorophyll d and f, reduces competition between species in light-limiting environments, and permits them to thrive in niches enriched in far-red light. We examined global transcriptome changes due to changing the culture light conditions in Acaryochloris marina, a chlorophyll d-containing cyanobacterium. We identified the functional category of 'photosynthesis' as the most down-regulated and the category of 'cell wall/membrane biogenesis' as the most up-regulated through a functional enrichment analysis of genes differentially expressed. Within the category of 'cell wall/membrane biogenesis', genes encoding glycosysltransferases accumulated the most in response to far-red light. Further experimental results confirmed that cells grown under far-red light form biofilms with a significantly increased adherence compared to cells grown under white light. Taken together, these results indicate that Acaryochloris marina shifts its lifestyle from a planktonic state under white light to an immobilized state under far-red light.
Modelling the Characteristic Residues of Chlorophyll f Synthase (ChlF) from Halomicronema Hongdechloris to Determine Its Reaction Mechanism
Publisher: MDPI AG
Date: 30-08-2023
DOI: 10.20944/PREPRINTS202308.2051.V1
Abstract: Photosystem II (PSII) is a quinone-utilising photosynthetic system that converts light energy into chemical energy and catalyses the splitting of water. PsbA (D1) and PsbD (D2) are the core subunits of the reaction centre that provide most of the ligands to the redox-active cofactors and exhibit photooxidoreductase activities that convert quinone and water into quinol and oxygen. This analysis explored the putative uncoupled electron transfer pathways surrounding P680+ induced by far-red light (FRL) based on photosystem II (PSII) complexes containing substituted D1 subunits in Halomicronema hongdechloris. Chlorophyll f-synthase (ChlF) is a D1 protein paralog. Modelling PSII-ChlF complexes determined several key protein motifs of ChlF. The PSII complexes showed a dysfunctional Mn4CaO5 cluster if ChlF replaced the D1 protein. We propose the mechanism of chlorophyll f synthesis from chlorophyll a via free radical chemistry in an oxygenated environment created by over-excited pheophytin a and an inactive water splitting reaction due to an uncoupled Mn4CaO5 cluster in PSII-ChlF complexes. The role of ChlF in the formation of an inactive PSII reaction centre is under debate and the putative mechanisms of chlorophyll biosynthesis are discussed.
Phylogenetic analysis of the light-harvesting system in Chromera velia
Publisher: Springer Science and Business Media LLC
Date: 10-12-2012
DOI: 10.1007/S11120-011-9710-9
Abstract: Chromera velia is a newly discovered photosynthetic eukaryotic alga that has functional chloroplasts closely related to the apicoplast of apicomplexan parasites. Recently, the chloroplast in C. velia was shown to be derived from the red algal lineage. Light-harvesting protein complexes (LHC), which are a group of proteins involved in photon capture and energy transfer in photosynthesis, are important for photosynthesis efficiency, photo-adaptation/accumulation and photo-protection. Although these proteins are encoded by genes located in the nucleus, LHC peptides migrate and function in the chloroplast, hence the LHC may have a different evolutionary history compared to chloroplast evolution. Here, we compare the phylogenetic relationship of the C. velia LHCs to LHCs from other photosynthetic organisms. Twenty-three LHC homologues retrieved from C. velia EST sequences were aligned according to their conserved regions. The C. velia LHCs are positioned in four separate groups on trees constructed by neighbour-joining, maximum likelihood and Bayesian methods. A major group of seventeen LHCs from C. velia formed a separate cluster that was closest to dinoflagellate LHC, and to LHC and fucoxanthin chlorophyll-binding proteins from diatoms. One C. velia LHC sequence grouped with LI1818/LI818-like proteins, which were recently identified as environmental stress-induced protein complexes. Only three LHC homologues from C. velia grouped with the LHCs from red algae.
A cross‐scale analysis to understand and quantify the effects of photosynthetic enhancement on crop growth and yield across environments
Publisher: Wiley
Date: 20-10-2023
DOI: 10.1111/PCE.14453
Abstract: Photosynthetic manipulation provides new opportunities for enhancing crop yield. However, understanding and quantifying the importance of in idual and multiple manipulations on the seasonal biomass growth and yield performance of target crops across variable production environments is limited. Using a state‐of‐the‐art cross‐scale model in the APSIM platform we predicted the impact of altering photosynthesis on the enzyme‐limited ( A c ) and electron transport‐limited ( A j ) rates, seasonal dynamics in canopy photosynthesis, biomass growth, and yield formation via large multiyear‐by‐location crop growth simulations. A broad list of promising strategies to improve photosynthesis for C 3 wheat and C 4 sorghum were simulated. In the top decile of seasonal outcomes, yield gains were predicted to be modest, ranging between 0% and 8%, depending on the manipulation and crop type. We report how photosynthetic enhancement can affect the timing and severity of water and nitrogen stress on the growing crop, resulting in nonintuitive seasonal crop dynamics and yield outcomes. We predicted that strategies enhancing A c alone generate more consistent but smaller yield gains across all water and nitrogen environments, A j enhancement alone generates larger gains but is undesirable in more marginal environments. Large increases in both A c and A j generate the highest gains across all environments. Yield outcomes of the tested manipulation strategies were predicted and compared for realistic Australian wheat and sorghum production. This study uniquely unpacks complex cross‐scale interactions between photosynthesis and seasonal crop dynamics and improves understanding and quantification of the potential impact of photosynthesis traits (or lack of it) for crop improvement research.
In vitro Conversion of Vinyl to Formyl Groups in Naturally Occurring Chlorophylls
Publisher: Springer Science and Business Media LLC
Date: 14-08-2014
DOI: 10.1038/SREP06069
Hydroxylation of the C132 and C18 carbons of chlorophylls by heme and molecular oxygen
Publisher: World Scientific Pub Co Pte Lt
Date: 09-2015
DOI: 10.1142/S1088424615500571
Abstract: Following extraction from photosynthetic organisms, chlorophylls are prone to reactions including demetalation, dephytylation and specific oxidations of the exocyclic ring E, termed allomerizations. Allomerization of chlorophylls has been well-characterized in methanol and to a lesser extent in aqueous solution. Here we detail novel allomerization-like reactions of chlorophyll a and chlorophyll b. In the presence of heme, detergent-solubilized chlorophyll a is hydroxylated at its C 13 2 position in ring E and, surprisingly, the C 18 position in ring D. Two major oxidation products are synthesized — a C 13 2 - OH and a C 13 2 - OH , C 18- OH derivative of chlorophyll a. We track the origin of the oxygen atoms added in these hydroxylated chlorophylls using 18 O 2 labeling and demonstrate that the additional oxygen atoms are derived from molecular oxygen. A similar heme-catalyzed reaction is also observed using chlorophyll b as a substrate. These results highlight the need for care when dealing with extracted chlorophylls and demonstrate an unusual hydroxylation of the C 18 position of chlorophylls in the presence of heme.
The Complex Transcriptional Response of Acaryochloris marina to Different Oxygen Levels.
Publisher: Oxford University Press (OUP)
Date: 02-2017
Abstract: Ancient oxygenic photosynthetic prokaryotes produced oxygen as a waste product, but existed for a long time under an oxygen-free (anoxic) atmosphere, before an oxic atmosphere emerged. The change in oxygen levels in the atmosphere influenced the chemistry and structure of many enzymes that contained prosthetic groups that were inactivated by oxygen. In the genome of Acaryochloris marina, multiple gene copies exist for proteins that are normally encoded by a single gene copy in other cyanobacteria. Using high throughput RNA sequencing to profile transcriptome responses from cells grown under microoxic and hyperoxic conditions, we detected 8446 transcripts out of the 8462 annotated genes in the Cyanobase database. Two-thirds of the 50 most abundant transcripts are key proteins in photosynthesis. Microoxic conditions negatively affected the levels of expression of genes encoding photosynthetic complexes, with the exception of some subunits. In addition to the known regulation of the multiple copies of psbA, we detected a similar transcriptional pattern for psbJ and psbU, which might play a key role in the altered components of photosystem II. Furthermore, regulation of genes encoding proteins important for reactive oxygen species-scavenging is discussed at genome level, including, for the first time, specific small RNAs having possible regulatory roles under varying oxygen levels.
Endolithic chlorophyll d-containing phototrophs
Publisher: Springer Science and Business Media LLC
Date: 16-12-2010
Chromatic photoacclimation, photosynthetic electron transport and oxygen evolution in the Chlorophyll d-containing oxyphotobacterium Acaryochloris marina
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.BBABIO.2006.11.014
Abstract: Changes in photosynthetic pigment ratios showed that the Chlorophyll d-dominated oxyphotobacterium Acaryochloris marina was able to photoacclimate to different light regimes. Chl d per cell were higher in cultures grown under low irradiance and red or green light compared to those found when grown under high white light, but phycocyanin/Chl d and carotenoid/Chl d indices under the corresponding conditions were lower. Chl a, considered an accessory pigment in this organism, decreased respective to Chl d in low irradiance and low intensity non-white light sources. Blue diode PAM (Pulse Amplitude Modulation) fluorometry was able to be used to measure photosynthesis in Acaryochloris. Light response curves for Acaryochloris were created using both PAM and O(2) electrode. A linear relationship was found between electron transport rate (ETR), measured using a PAM fluorometer, and oxygen evolution (net and gross photosynthesis). Gross photosynthesis and ETR were directly proportional to one another. The optimum light for white light (quartz halogen) was about 206+/-51 micromol m(-2) s(-1) (PAR) (Photosynthetically Active Radiation), whereas for red light (red diodes) the optimum light was lower (109+/-27 micromol m(-2) s(-1) (PAR)). The maximum mean gross photosynthetic rate of Acaryochloris was 73+/-7 micromol mg Chl d(-1) h(-1). The gross photosynthesis/respiration ratio (P(g)/R) of Acaryochloris under optimum conditions was about 4.02+/-1.69. The implications of our findings will be discussed in relation to how photosynthesis is regulated in Acaryochloris.
Chlorophyll f can replace chlorophyll a in the soluble antenna of dinoflagellates
Publisher: Springer Science and Business Media LLC
Date: 06-01-2022
DOI: 10.1007/S11120-021-00890-8
Abstract: Chlorophyll f is a new type of chlorophyll isolated from cyanobacteria. The absorption and fluorescence characteristics of chlorophyll f permit these oxygenic-photosynthetic organisms to thrive in environments where white light is scarce but far-red light is abundant. To explore the ligand properties of chlorophyll f and its energy transfer profiles we established two different in vitro reconstitution systems. The reconstituted peridinin-chlorophyll f protein complex (chlorophyll f-PCP) showed a stoichiometry ratio of 4:1 between peridinin and chlorophyll f, consistent with the peridinin:chlorophyll a ratio from native PCP complexes. Using emission wavelength at 712 nm, the excitation fluorescence featured a broad peak at 453 nm and a shoulder at 511 nm confirming energy transfer from peridinin to chlorophyll f. In addition, by using a synthetic peptide mimicking the first transmembrane helix of light-harvesting chlorophyll proteins of plants, we report that chlorophyll f, similarly to chlorophyll b, did not interact with the peptide contrarily to chlorophyll a, confirming the accessory role of chlorophyll f in photosystems. The binding of chlorophyll f, even in the presence of chlorophylls a and b, by PCP complexes shows the flexibility of chlorophyll-protein complexes and provides an opportunity for the introduction of new chlorophyll species to extend the photosynthetic spectral range.
Molecular Basis of Antenna System Adaptation in a Chl d-Containing Organism
Publisher: Springer Netherlands
Date: 2008
Genomic and transcriptomic insights into the survival of the subaerial cyanobacterium Nostoc flagelliforme in arid and exposed habitats
Publisher: Wiley
Date: 27-01-2019
Abstract: The cyanobacterium Nostoc flagelliforme is an extremophile that thrives under extraordinary desiccation and ultraviolet (UV) radiation conditions. To investigate its survival strategies, we performed whole-genome sequencing of N. flagelliforme CCNUN1 and transcriptional profiling of its field populations upon rehydration in BG11 medium. The genome of N. flagelliforme is 10.23 Mb in size and contains 10 825 predicted protein-encoding genes, making it one of the largest complete genomes of cyanobacteria reported to date. Comparative genomics analysis among 20 cyanobacterial strains revealed that genes related to DNA replication, recombination and repair had disproportionately high contributions to the genome expansion. The ability of N. flagelliforme to thrive under extreme abiotic stresses is supported by the acquisition of genes involved in the protection of photosynthetic apparatus, the formation of monounsaturated fatty acids, responses to UV radiation, and a peculiar role of ornithine metabolism. Transcriptome analysis revealed a distinct acclimation strategy to rehydration, including the strong constitutive expression of genes encoding photosystem I assembly factors and the involvement of post-transcriptional control mechanisms of photosynthetic resuscitation. Our results provide insights into the adaptive mechanisms of subaerial cyanobacteria in their harsh habitats and have important implications to understand the evolutionary transition of cyanobacteria from aquatic environments to terrestrial ecosystems.
Effects of Anaerobic Conditions on Photosynthetic Units of Acaryochloris Marina
Publisher: Springer Berlin Heidelberg
Date: 2013
The C21-formyl group in chlorophyll f originates from molecular oxygen
Publisher: Elsevier BV
Date: 11-2017
Genomic Contributions to Understanding the Evolution of Red Algal Plastids and Pigment Biosynthesis
Publisher: Springer Netherlands
Date: 2010
Photosynthetic Apparatus of Antenna-reaction Centres Supercomplexes in Oxyphotobacteria: Insight through Significance of Pcb/IsiA Proteins
Publisher: Springer Science and Business Media LLC
Date: 11-2005
DOI: 10.1007/S11120-005-1330-9
Abstract: In this Review we give an overview of the structure and function of the membrane-bound photosynthetic antenna reaction centre complexes present in oxyphotobacteria. We summarise how variations in the organisation of these complexes have enabled oxyphotobacteria to exploit different ecological niches and discuss the evolutionary relationships of the IsiA/Pcb family of pigment-binding proteins.
Spectroscopic Properties of Chlorophyll f
Publisher: American Chemical Society (ACS)
Date: 06-05-2013
DOI: 10.1021/JP402413D
Abstract: The absorption and fluorescence spectra of chlorophyll f (newly discovered in 2010) have been measured in acetone and methanol at different temperatures. The spectral analysis and assignment are compared with the spectra of chlorophyll a and d under the same experimental conditions. The spectroscopic properties of these chlorophylls have further been studied by the aid of density functional CAM-B3LYP and high-level symmetric adapted coupled-cluster configuration interaction calculations. The main Q and Soret bands and possible sidebands of chlorophylls have been determined. The photophysical properties of chlorophyll f are discussed.
The Function of MgDVP in a Chlorophyll d-Containing Organism
Publisher: Springer Netherlands
Date: 2008
Niche adaptation and genome expansion in the chlorophyll d -producing cyanobacterium Acaryochloris marina
Publisher: Proceedings of the National Academy of Sciences
Date: 12-02-2008
Abstract: Acaryochloris marina is a unique cyanobacterium that is able to produce chlorophyll d as its primary photosynthetic pigment and thus efficiently use far-red light for photosynthesis. Acaryochloris species have been isolated from marine environments in association with other oxygenic phototrophs, which may have driven the niche-filling introduction of chlorophyll d . To investigate these unique adaptations, we have sequenced the complete genome of A. marina . The DNA content of A. marina is composed of 8.3 million base pairs, which is among the largest bacterial genomes sequenced thus far. This large array of genomic data is distributed into nine single-copy plasmids that code for % of the putative ORFs. Heavy duplication of genes related to DNA repair and recombination (primarily recA ) and transposable elements could account for genetic mobility and genome expansion. We discuss points of interest for the biosynthesis of the unusual pigments chlorophyll d and α-carotene and genes responsible for previously studied phycobilin aggregates. Our analysis also reveals that A. marina carries a unique complement of genes for these phycobiliproteins in relation to those coding for antenna proteins related to those in Prochlorococcus species. The global replacement of major photosynthetic pigments appears to have incurred only minimal specializations in reaction center proteins to accommodate these alternate pigments. These features clearly show that the genus Acaryochloris is a fitting candidate for understanding genome expansion, gene acquisition, ecological adaptation, and photosystem modification in the cyanobacteria.
Extending the limits of natural photosynthesis and implications for technical light harvesting
Publisher: World Scientific Pub Co Pte Ltd
Date: 2013
DOI: 10.1142/S1088424612300108
Abstract: Photosynthetic organisms provide, directly or indirectly, the energy that sustains life on earth by harvesting light from the sun. The amount of light impinging on the surface of the earth vastly surpasses the energy needs of life including man. Harvesting the sun is, therefore, an option for a sustainable energy source: directly by improving biomass production, indirectly by coupling it to the production of hydrogen for fuel or, conceptually, by using photosynthetic strategies for technological solutions based on non-biological or hybrid materials. In this review, we summarize the various light climates on earth, the primary reactions responsible for light harvesting and transduction to chemical energy in photosynthesis, and the mechanisms of competitively adapting the photosynthetic apparatus to the ever-changing light conditions. The focus is on oxygenic photosynthesis, its adaptation to the various light-climates by specialized pigments and on the extension of its limits by the evolution of red-shifted chlorophylls. The implications for potential technical solutions are briefly discussed.
A unique regulation of the expression of the psbA, psbD, and psbE genes, encoding the D1, D2 and cytochrome b559 subunits of the Photosystem II complex in the chlorophyll d containing cyanobacterium A
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.BBABIO.2012.04.010
Abstract: Photosynthetic electron transport, chromatic photoacclirnation and expression of the genes encoding the 01, 02, and cytochrome b559 subunits of the Photosystem II complex were studied in the chlorophyll d containing cyanobacterium Acaryochloris marina MBIC11017 under various environmental conditions. During oxygen deprivation and inhibition of photosynthetic electron transport by dibromothymoquinone the psbA1 gene encoding a 01' isoform was induced. All of the three psbA and one of the three psbD (psbD2) genes, encoding two different isoforms of the 01 and the abundant isoform of the 02 proteins, respectively were induced under exposure to UV-B radiation and high intensity visible light. Under far red light the amount of Photosystem II complexes increased, and expression of the psbE2 gene encoding the alpha-subunit of cytochrome b559 was enhanced. However, the psbF and psbE1 genes encoding the beta- and another isoform of alpha-cytochrome b559, respectively remained lowly expressed under all conditions. Far red light also induced the psbD3 gene encoding a 02' isoform whose primary structure is different from the abundant 02 isoform. psbD3 was also induced under low intensity visible light, when chromatic photoacclimation was indicated by a red-shifted absorption of chlorophyll d. Our results show that differential expression of multigene families encoding different isoforms of 01 and 02 plays an important role in the acclimation of A. marina to contrasting environmental conditions. Moreover, the disproportionate quantity of transcripts of the alpha and beta subunits of cytochrome b559 implies the existence of an alpha-alpha homodimer organization of cytochrome b559 in Photosystem II complexes.
Solvent Effect on Supramolecular Self-Assembly of Chlorophylls a on Chemically Reduced Graphene Oxide
Publisher: American Chemical Society (ACS)
Date: 21-10-2020
A method for growing a monospecific epilithic cyanobacterial biofilm for use in marine ecological experiments
Publisher: Elsevier BV
Date: 07-2016
A cyanobacterium that contains chlorophyllf- a red-absorbing photopigment
Publisher: Wiley
Date: 13-07-2012
DOI: 10.1016/J.FEBSLET.2012.06.045
Abstract: A Chl f-containing filamentous cyanobacterium was purified from stromatolites and named as Halomicronema hongdechloris gen., sp. nov. after its phylogenetic classification and the morphological characteristics. Hongdechloris contains four main carotenoids and two chlorophylls, a and f. The ratio of Chl f to Chl a is reversibly changed from 1:8 under red light to an undetectable level of Chl f under white-light culture conditions. Phycobiliproteins were induced under white light growth conditions. A fluorescence emission peak of 748 nm was identified as due to Chl f. The results suggest that Chl f is a red-light inducible chlorophyll.
Increased growth and pigment content ofChromera veliain mixotrophic culture
Publisher: Oxford University Press (OUP)
Date: 16-01-2014
Abstract: The alveolate microalga Chromera velia is an evolutionarily significant organism, representing the closest photosynthetic relative of the parasitic Apicomplexa. Chromera velia has been detected in and isolated from several stony corals and can be readily cultured in vitro under strictly autotrophic conditions. However, little is known about the ecology of this organism in the coral holobiont, an environment in which it could potentially access abundant organic carbon sources. To understand the response of C. velia to ecologically relevant organic compounds in vitro, we tested a mixotrophic culture strategy by supplementing inorganic f-medium with sugars, sugar-alcohols, organic acids and amino acids. For 15 of the 18 tested growth media, culture growth rate was significantly higher than that of strictly autotrophic cultures, and in three of these, a significant increase in maximum culture density was observed. In cultures supplemented with glutamate or glycine, the chlorophyll content per cell was up to 11-fold higher than cultures grown in standard inorganic media. Together, the in vitro culture growth and pigment responses demonstrate an ability to respond to nutritional resources when available. We propose that C. velia is a facultative opportunist in environments similarly enriched in such organic compounds, such as the coral holobiont.
Raman properties of chlorophyll d, the major pigment of Acaryochloris marina: studies using both Raman spectroscopy and density functional theory
Publisher: Elsevier BV
Date: 02-2004
DOI: 10.1016/S1386-1425(03)00258-0
Abstract: The Raman spectroscopy of purified chlorophyll (Chl) d extracted from Acaryochloris marina has been measured over the wide region of 250-3200 cm(-1) at 77 K following excitation of its Soret band at 488 nm and analyzed with the aid of hybrid density-functional vibrational analyses. A Raman peak specific to Chl d, which arises from the formyl group 3(1) C=O stretching, was clearly observed at 1659 cm(-1) with medium intensity. Peaks due to other C=O stretching vibrations of the 13(1) keto-, 13(3) ester- and 17(3) groups were also observed. Four very strong peaks were observed in the range of 1000-1600 cm(-1), assigned to the CC stretching and mixtures of the CH3 bend and CN stretching. CCC and NCC bending contribute to medium intensity peaks at 986 and 915 cm(-1). Out-of-plane CH bending at Chl d methine sites 10, 5 and 20 contribute to observed peaks at 885, 864 and 853 cm(-1), respectively. A few modes involving the MgN stretching and MgNC bending motions were observed in the very low frequency range. Density functional theory (DFT) calculations have been used to make assignments on the observed Raman spectrum and the DFT results have been found to be in good agreement with the experimental results.
A new chlorophyll d-containing cyanobacterium: evidence for niche adaptation in the genus Acaryochloris
Publisher: Springer Science and Business Media LLC
Date: 27-05-2010
Abstract: Chlorophyll d is a photosynthetic pigment that, based on chemical analyses, has only recently been recognized to be widespread in oceanic and lacustrine environments. However, the ersity of organisms harbouring this pigment is not known. Until now, the unicellular cyanobacterium Acaryochloris marina is the only characterized organism that uses chlorophyll d as a major photopigment. In this study we describe a new cyanobacterium possessing a high amount of chlorophyll d, which was isolated from waters around Heron Island, Great Barrier Reef (23° 26' 31.2″ S, 151° 54' 50.4″ E). The 16S ribosomal RNA is 2% ergent from the two previously described isolates of A. marina, which were isolated from waters around the Palau islands (Pacific Ocean) and the Salton Sea lake (California), suggesting that it belongs to a different clade within the genus Acaryochloris. An overview sequence analysis of its genome based on Illumina technology yielded 871 contigs with an accumulated length of 8 371 965 nt. Their analysis revealed typical features associated with Acaryochloris, such as an extended gene family for chlorophyll-binding proteins. However, compared with A. marina MBIC11017, distinct genetic, morphological and physiological differences were observed. Light saturation is reached at lower light intensities, Chl d/a ratios are less variable with light intensity and the phycobiliprotein phycocyanin is lacking, suggesting that cyanobacteria of the genus Acaryochloris occur in distinct ecotypes. These data characterize Acaryochloris as a niche-adapted cyanobacterium and show that more rigorous attempts are worthwhile to isolate, cultivate and analyse chlorophyll d-containing cyanobacteria for understanding the ecophysiology of these organisms.
The Genome of Heliobacterium modesticaldum , a Phototrophic Representative of the Firmicutes Containing the Simplest Photosynthetic Appara
Publisher: American Society for Microbiology
Date: 07-2008
DOI: 10.1128/JB.00299-08
Abstract: Despite the fact that heliobacteria are the only phototrophic representatives of the bacterial phylum Firmicutes , genomic analyses of these organisms have yet to be reported. Here we describe the complete sequence and analysis of the genome of Heliobacterium modesticaldum , a thermophilic species belonging to this unique group of phototrophs. The genome is a single 3.1-Mb circular chromosome containing 3,138 open reading frames. As suspected from physiological studies of heliobacteria that have failed to show photoautotrophic growth, genes encoding enzymes for known autotrophic pathways in other phototrophic organisms, including ribulose bisphosphate carboxylase (Calvin cycle), citrate lyase (reverse citric acid cycle), and malyl coenzyme A lyase (3-hydroxypropionate pathway), are not present in the H. modesticaldum genome. Thus, heliobacteria appear to be the only known anaerobic anoxygenic phototrophs that are not capable of autotrophy. Although for some cellular activities, such as nitrogen fixation, there is a full complement of genes in H. modesticaldum , other processes, including carbon metabolism and endosporulation, are more genetically streamlined than they are in most other low-G+C gram-positive bacteria. Moreover, several genes encoding photosynthetic functions in phototrophic purple bacteria are not present in the heliobacteria. In contrast to the nutritional flexibility of many anoxygenic phototrophs, the complete genome sequence of H. modesticaldum reveals an organism with a notable degree of metabolic specialization and genomic reduction.
The specificity of the bilin lyase CpcS for chromophore attachment to allophycocyanin in the chlorophyll f-containing cyanobacterium Halomicronima hongdechloris
Publisher: Springer Science and Business Media LLC
Date: 26-09-2021
DOI: 10.1007/S11120-021-00878-4
Abstract: Phycobilisomes are light-harvesting antenna complexes of cyanobacteria and red algae that are comprised of chromoproteins called phycobiliproteins. PBS core structures are made up of allophycocyanin subunits. Halomicronema hongdechloris (H. hongdechloris) is one of the cyanobacteria that produce chlorophyll f (Chl f) under far-red light and is regulated by the Far-Red Light Photoacclimation gene cluster. There are five genes encoding APC in this specific gene cluster, and they are responsible for assembling the red-shifted PBS in H. hongdechloris grown under far-red light. In this study, the five apc genes located in the FaRLiP gene cluster were heterologously expressed in an Escherichia coli reconstitution system. The canonical APC-encoding genes were also constructed in the same system for comparison. Additionally, five annotated phycobiliprotein lyase-encoding genes (cpcS) from the H. hongdechloris genome were phylogenetically classified and experimentally tested for their catalytic properties including their contribution to the shifted absorption of PBS. Through analysis of recombinant proteins, we determined that the heterodimer of CpcS-I and CpcU are able to ligate a chromophore to the APC-α/APC-β subunits. We discuss some hypotheses towards understanding the roles of the specialised APC and contributions of PBP lyases.
Nomenclature for membrane-bound light-harvesting complexes of cyanobacteria
Publisher: Springer Science and Business Media LLC
Date: 03-10-2007
DOI: 10.1007/S11120-007-9255-0
Abstract: Accessory chlorophyll-binding proteins (CBP) in cyanobacteria have six transmembrane helices and about 11 conserved His residues that might participate in chlorophyll binding. In various species of cyanobacteria, the CBP proteins bind different types of chlorophylls, including chlorophylls a, b, d and inyl-chlorophyll a, b. The CBP proteins do not belong to the light-harvesting complexes (LHC) superfamily of plant and algae. The proposed new name of CBP for this class of proteins, which is a unique accessory light-harvesting superfamily in cyanobacteria, clarifies the confusion of names of prochlorophytes chlorophyll binding protein (Pcb), PSII-like light-harvesting proteins and iron-stress-induced protein A (IsiA). The CBP complexes are a member of a larger family that includes the chlorophyll a-binding proteins CP43 and CP47 that function as core antennas of photosystem II.
Excitation Dynamics in the Core Antenna in the Photosystem I Reaction Center of the Chlorophyll d-Containing Photosynthetic Prokaryote Acaryochloris marina
Publisher: American Chemical Society (ACS)
Date: 15-01-2003
DOI: 10.1021/JP0268260
Functioning of the Bidirectional Hydrogenase in Different Unicellular Cyanobacteria
Publisher: Springer Berlin Heidelberg
Date: 2013
Modelling the Structure of the IsiA-PS I Supercomplex
Publisher: Springer Netherlands
Date: 2008
Spectral properties of bacteriophytochrome AM1_5894 in the chlorophyll dcontaining cyanobacterium Acaryochloris marina.
Publisher: Springer Science and Business Media LLC
Date: 10-06-2016
DOI: 10.1038/SREP27547
Abstract: Acaryochloris marina , a unicellular oxygenic photosynthetic cyanobacterium, has uniquely adapted to far-red light-enriched environments using red-shifted chlorophyll d . To understand red-light use in Acaryochloris , the genome of this cyanobacterium was searched for red/far-red light photoreceptors from the phytochrome family, resulting in identification of a putative bacteriophytochrome AM1_5894 . AM1_5894 contains three standard domains of photosensory components as well as a putative C-terminal signal transduction component consisting of a histidine kinase and receiver domain. The photosensory domains of AM1_5894 autocatalytically assemble with biliverdin in a covalent fashion. This assembled AM1_5894 shows the typical photoreversible conversion of bacterial phytochromes with a ground-state red-light absorbing (Pr) form with λ BV max [Pr] 705 nm, and a red-light inducible far-red light absorbing (Pfr) form with λ BV max [Pfr] 758 nm. Surprisingly, AM1_5894 also autocatalytically assembles with phycocyanobilin, involving photoreversible conversion of λ PCB max [Pr] 682 nm and λ PCB max [Pfr] 734 nm, respectively. Our results suggest phycocyanobilin is also covalently bound to AM1_5894, while mutation of a cysteine residue (Cys11Ser) abolishes this covalent binding. The physiological function of AM1_5894 in cyanobacteria containing red-shifted chlorophylls is discussed.
Theoretical study on the thermodynamic properties of chlorophyll d-peptides coordinating ligand
Publisher: Elsevier BV
Date: 06-2007
DOI: 10.1016/J.BBABIO.2007.01.006
Abstract: The chlorophyll d containing cyanobacterium, Acaryochloris marina has provided a model system for the study of chlorophyll replacement in the function of oxygenic photosynthesis. Chlorophyll d replaces most functions of chlorophyll a in Acaryochloris marina. It not only functions as the major light-harvesting pigment, but also acts as an electron transfer cofactor in the primary charge separation reaction in the two photosystems. The Mg-chlorophyll d-peptide coordinating interaction between the amino acid residues and chlorophylls using the latest semi-empirical PM5 method were examined. It is suggested that chlorophyll d possesses similar coordination ligand properties to chlorophyll a, but chlorophyll b possesses different ligand properties. Compared with other studies involving theoretical correlation and our prior experiments, this study suggests that the chlorophyll a-bound proteins will bind chlorophyll d without difficulty when chlorophyll d is available.
Spectral expansion and antenna reduction can enhance photosynthesis for energy production
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.CBPA.2013.03.031
Abstract: We consider two approaches for improving the efficiency of photosynthesis: the expansion of the solar spectrum that drives oxygenic photosynthesis and the reduction of antenna systems that couple to the photochemical reaction center. The first approach can possibly result in an increase of 19% in the number of photons available per unit area if the photosynthetically active radiation spectrum is expanded to 750 nm. The second approach can in principle shift the photosynthesis light response curve to significantly higher intensities, thereby reducing the amount of excess light, which is absorbed photons in excess of the number that can be utilized. The implementation of these approaches may lead to apparent improvement in photosynthetic efficiency in many but not all the cases.
Excited state properties of chlorophyll f in organic solvents at ambient and cryogenic temperatures
Publisher: Springer Science and Business Media LLC
Date: 19-02-2014
DOI: 10.1007/S11120-014-9981-Z
Abstract: Chlorophyll f is a photosynthetic pigment that was discovered in 2010. In this study, we present investigations on spectral and dynamic characteristics of singlet-excited and triplet states of Chl f with the application of ultrafast time-resolved absorption and fluorescence spectroscopies. The pigment was studied at room temperature in two organic solvents: pyridine and diethyl ether that have different characters of coordination of the chlorophyll magnesium (Mg) atom (hexa- and penta-coordination, respectively). Cryogenic measurements (77 K) were performed in 2-methyltetrahydrofuran (hexa-coordination). The singlet-excited state lifetime was measured to be 5.6 ns at room temperature regardless of Mg coordination and 8.1 ns at 77 K. The fluorescence quantum yield of Chl f was also determined in pyridine to be 0.16. The triplet state lifetime was studied in detail in pyridine at room temperature, and the inherent lifetime was estimated to ~150 μs. Selective measurements at 77 K demonstrated that the metastability of the triplet state greatly enhances, and its lifetime increases by a factor of more than three.
Chlorophyll Modifications and Their Spectral Extension in Oxygenic Photosynthesis
Publisher: Annual Reviews
Date: 02-06-2014
DOI: 10.1146/ANNUREV-BIOCHEM-072711-162943
Abstract: Chlorophylls are magnesium-tetrapyrrole molecules that play essential roles in photosynthesis. All chlorophylls have similar five-membered ring structures, with variations in the side chains and/or reduction states. Formyl group substitutions on the side chains of chlorophyll a result in the different absorption properties of chlorophyll b, chlorophyll d, and chlorophyll f. These formyl substitution derivatives exhibit different spectral shifts according to the formyl substitution position. Not only does the presence of various types of chlorophylls allow the photosynthetic organism to harvest sunlight at different wavelengths to enhance light energy input, but the pigment composition of oxygenic photosynthetic organisms also reflects the spectral properties on the surface of the Earth. Two major environmental influencing factors are light and oxygen levels, which may play central roles in the regulatory pathways leading to the different chlorophylls. I review the biochemical processes of chlorophyll biosynthesis and their regulatory mechanisms.
Widespread occurrence and unexpected diversity of red‐shifted chlorophyll producing cyanobacteria in humid subtropical forest ecosystems
Publisher: Wiley
Date: 21-03-2019
Abstract: Discovery of red-shifted chlorophyll d and f in cyanobacteria has opened up new avenues to estimate global carbon fixation driven by far-red light. Shaded habitats in humid subtropical forest ecosystems contain an increased proportion of far-red light components relative to residual white light. After an extensive survey of shaded ecosystems within subtropical forests, wide occurrence of red-shifted chlorophyll-producing cyanobacteria was demonstrated by isolated Chl f-producing and Chl d-containing cyanobacteria. Chl f-producing cyanobacteria were classified into the genera of Aphanocapsa and Chroococcidiopsis and two undescribed genera within Leptolyngbyaceae. Newly isolated Chl d-containing Acaryochloris sp. CCNUM4 showed the closest phylogenetic relationship with Acaryochloris species isolated from marine environments. Acaryochloris sp. CCNUM4 produced Chl d as major photopigment, and Chl f-producing cyanobacteria use Chl a under white light conditions but Chl a + f under far-red light conditions. Their habitats are widely distributed in subtropical forest ecosystems and varied from mosses on limestone to macrophyte and freshwater in the streams and ponds. This study presents a significant advance in the knowledge of distribution and ersity of red-shifted chlorophyll-producing cyanobacteria in terrestrial ecosystems. The results suggest that Chl f-producing and Chl d-containing cyanobacteria might be important primary producers in far-red light dominant niches worldwide.
A niche for cyanobacteria containing chlorophyll d
Publisher: Springer Science and Business Media LLC
Date: 02-2005
DOI: 10.1038/433820A
Abstract: The cyanobacterium known as Acaryochloris marina is a unique phototroph that uses chlorophyll d as its principal light-harvesting pigment instead of chlorophyll a, the form commonly found in plants, algae and other cyanobacteria this means that it depends on far-red light for photosynthesis. Here we demonstrate photosynthetic activity in Acaryochloris-like phototrophs that live underneath minute coral-reef invertebrates (didemnid ascidians) in a shaded niche enriched in near-infrared light. This discovery clarifies how these cyanobacteria are able to thrive as free-living organisms in their natural habitat.
Draft Genome Sequence of the Filamentous Cyanobacterium Leptolyngbya sp. Strain Heron Island J, Exhibiting Chromatic Acclimation
Publisher: American Society for Microbiology
Date: 27-02-2014
Abstract: Leptolyngbya sp. strain Heron Island is a cyanobacterium exhibiting chromatic acclimation. However, this strain has strong interactions with other bacteria, making it impossible to obtain axenic cultures for sequencing. A protocol involving an analysis of tetranucleotide frequencies, G+C content, and BLAST searches has been described for separating the cyanobacterial scaffolds from those of its cooccurring bacteria.
Spectral signatures of five hydroxymethyl chlorophyll a derivatives chemically derived from chlorophyll b or chlorophyll f
Publisher: Springer Science and Business Media LLC
Date: 02-01-2019
DOI: 10.1007/S11120-018-00611-8
Abstract: Chlorophylls (Chls) are pigments involved in light capture and light reactions in photosynthesis. Chl a, Chl b, Chl d, and Chl f are characterized by unique absorbance maxima in the blue (Soret) and red (Q
The molecular structure of the IsiA–Photosystem I supercomplex, modelled from high-resolution, crystal structures of Photosystem I and the CP43 protein
Publisher: Elsevier BV
Date: 04-2010
DOI: 10.1016/J.BBABIO.2010.01.002
Abstract: We present the molecular structure of the IsiA-Photosystem I (PSI) supercomplex, inferred from high-resolution, crystal structures of PSI and the CP43 protein. The structure of iron-stress-induced A protein (IsiA) is similar to that of CP43, albeit with the difference that IsiA is associated with 15 chlorophylls (Chls), one more than previously assumed. The membrane-spanning helices of IsiA contain hydrophilic residues many of which bind Chl. The optimal structure of the IsiA-PSI supercomplex was inferred by systematically rearranging the IsiA monomers and PSI trimer in relation to each other. For each of the 6,969,600 structural configurations considered, we counted the number of optimal Chl-Chl connections (i.e., cases where Chl-bound Mg atoms are <or=25A apart). Fifty of these configurations were found to have optimal energy-transfer potential. The 50 configurations could be ided into three variants one of these, comprising 36 similar configurations, was found to be superior to the other configurations in terms of its potential to transfer excitation energy to the reaction centres under low-light conditions and its potential to dissipate excess energy under high-light conditions. Compared to the assumed model [Biochemistry 42 (2003) 3180-3188], the new Chl increases by 7% the ability of IsiA to harvest sunlight while the rearrangement of the constituent components of the IsiA-PSI supercomplex increases by 228% the energy-transfer potential. In conclusion, our model allows us to explain how the IsiA-PSI supercomplex may act as an efficient light-harvesting structure under low-light conditions and as an efficient dissipater of excess energy under high-light conditions.
Molecular Mechanism of Photosynthesis Driven by Red-Shifted Chlorophylls
Publisher: Springer Singapore
Date: 2020
Influence of Structure on Binding of Chlorophylls to Peptide Ligands
Publisher: American Chemical Society (ACS)
Date: 26-01-2005
DOI: 10.1021/JA043462B
Abstract: Four classes of chlorophyll (Chl), a, b, c, and d, are involved in photosynthesis within cyanobacteria, algae, and plants. These classes have different evolutionary origins, chemical properties, and biological functions. Our results demonstrate that peptide-bound ligands provided by the imidazole group of histidine and the charge-compensated glutamate-arginine ion pair readily form coordination bonds with Chls a and d but do not interact significantly with Chls b and c. These ligands are apparently not sufficiently strong Lewis bases to displace strongly coordinated water from Chls b and c. These differences determine specificity of binding of Chls in light-harvesting complexes and play an important role in assembly of stable Chl-protein complexes, which has had a profound impact on the evolution of photosynthetic organisms.
Tracking the molecular evolution of photosynthesis through characterization of atomic contents of the photosynthetic units
Publisher: Springer Science and Business Media LLC
Date: 09-2008
DOI: 10.1007/S11120-008-9356-4
Abstract: Oxygen molecules have a great impact on protein evolution. We have performed a comparative study of key photosynthetic proteins in order to seek the answer to the question did the evolutionary substitution of oxygen- and nitrogen-containing residues in the photosynthetic proteins correspond to nutrient constraints and metabolic optimization? The D1 peptide in RC II complexes has higher oxygen-containing amino acid residues and PufL/PufM have lower oxygen content in their peptides. In this article, we also discuss the possible influences of micro-environment and the available nutrients on the protein structure and their atomic distribution.
Energy transfer in the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, analyzed by time-resolved fluorescence spectroscopies
Publisher: Springer Science and Business Media LLC
Date: 04-02-2015
DOI: 10.1007/S11120-015-0091-3
Abstract: We prepared thylakoid membranes from Halomicronema hongdechloris cells grown under white fluorescent light or light from far-red (740 nm) light-emitting diodes, and observed their energy-transfer processes shortly after light excitation. Excitation-relaxation processes were examined by steady-state and time-resolved fluorescence spectroscopies. Two time-resolved fluorescence techniques were used: time-correlated single photon counting and fluorescence up-conversion methods. The thylakoids from the cells grown under white light contained chlorophyll (Chl) a of different energies, but were devoid of Chl f. At room temperature, the excitation energy was equilibrated among the Chl a pools with a time constant of 6.6 ps. Conversely, the thylakoids from the cells grown under far-red light possessed both Chl a and Chl f. Two energy-transfer pathways from Chl a to Chl f were identified with time constants of 1.3 and 5.0 ps, and the excitation energy was equilibrated between the Chl a and Chl f pools at room temperature. We also examined the energy-transfer pathways from phycobilisome to the two photosystems under white-light cultivation.
A Red-Shifted Chlorophyll: Fig. 1
Publisher: American Association for the Advancement of Science (AAAS)
Date: 10-09-2010
Abstract: Among the first facts students learn about the natural world is that plants owe their green color to the pigment chlorophyll. There have actually been a handful of slightly different chlorophyll variants uncovered over the years, and Chen et al. (p. 1318 , published online 19 August) have found another in bacteria from Shark Bay, Australia. The chlorophyll variant displayed a red-shifted absorption spectrum, which extended into the near-infrared region due to the insertion of a formyl group on the molecule's periphery. The precise cellular function of the pigment awaits further study.
Excitation energy transfer from phycobiliprotein to chlorophyll d in intact cells of Acaryochloris marina studied by time- and wavelength-resolved fluorescence spectroscopy
Publisher: Springer Science and Business Media LLC
Date: 12-2005
DOI: 10.1039/B512350J
Abstract: The fluorescence decay spectra and the excitation energy transfer from the phycobiliproteins (PBP) to the chlorophyll-antennae of intact cells of the chlorophyll (Chl) d-dominated cyanobacterium Acaryochloris marina were investigated at 298 and 77 K by time- and wavelength-correlated single photon counting fluorescence spectroscopy. At 298 K it was found that (i) the fluorescence dynamics in A. marina is characterized by two emission peaks located at about 650 and 725 nm, (ii) the intensity of the 650 nm fluorescence depends strongly on the excitation wavelength, being high upon excitation of phycobiliprotein (PBP) at 632 nm but virtually absent upon excitation of chlorophyll at 430 nm, (iii) the 650 nm fluorescence band decayed predominantly with a lifetime of 70 +/- 20 ps, (iv) the 725 nm fluorescence, which was observed independent of the excitation wavelength, can be described by a three-exponential decay kinetics with lifetimes depending on the open or the closed state (F(0) or F(m)) of the reaction centre of Photosystem II (PS II). Based on the results of this study, it is inferred that the excitation energy transfer from phycobiliproteins to Chl d of PS II in A. marina occurs with a time constant of about 70 ps, which is about three times faster than the energy transfer from the phycobilisomes to PS II in the Chl a-containing cyanobacterium Synechococcus 6301. A similar fast PBP to Chl d excitation energy transfer was also observed at 77 K. At 77 K a small long-lived fluorescence decay component with a lifetime of 14 ns was observed in the 640-700 nm spectral range. However, it has a rather featureless spectrum, not typical for Chl a, and was only observed upon excitation at 400 nm but not upon excitation at 632 and 654 nm. Thus, this long-lived fluorescence component cannot be used as an indicator that the primary PS II donor of Acaryochloris marina contains Chl a.
Newly Isolated Chl d-Containing Cyanobacteria
Publisher: Springer Berlin Heidelberg
Date: 2013
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