ORCID Profile
0000-0002-7897-4038
Current Organisation
Umeå University
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Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.BBABIO.2011.05.002
Abstract: The five small CAB-like proteins (ScpA-E) of the cyanobacterium Synechocystis sp. PCC 6803 belong to the family of stress-induced light-harvesting-like proteins, but are constitutively expressed in a mutant deficient of Photosystem I (PSI). Using absorption, fluorescence and thermoluminescence measurements this PSI-less strain was compared with a mutant, in which all SCPs were additionally deleted. Depletion of SCPs led to structural rearrangements in Photosystem II (PSII): less photosystems were assembled and in these, the Q(B) site was modified. Despite the lower amount of PSII, the SCP-deficient cells contained the same amount of phycobilisomes (PBS) as the control. Although the excess PBS were functionally disconnected, their fluorescence was quenched under high irradiance by the activated Orange Carotenoid Protein (OCP). Additionally the amount of OCP, but not of the iron-stress induced protein (isiA), was higher in this SCP-depleted mutant compared with the control. As previously described, the lack of SCPs affects the chlorophyll biosynthesis (Vavilin, D., Brune, D. C., Vermaas, W. (2005) Biochim Biophys Acta 1708, 91-101). We demonstrate that chlorophyll synthesis is required for efficient PSII repair and that it is partly impaired in the absence of SCPs. At the same time, the amount of chlorophyll also seems to influence the expression of ScpC and ScpD.
Publisher: Portland Press Ltd.
Date: 20-12-2013
DOI: 10.1042/BJ20130196
Abstract: MMPs (matrix metalloproteases) are a family of zinc-dependent endopeptidases widely distributed throughout all kingdoms of life. In mammals, MMPs play key roles in many physiological and pathological processes, including remodelling of the extracellular matrix. In the genome of the annual plant Arabidopsis thaliana, five MMP-like proteins (At-MMPs) are encoded, but their function is unknown. Previous work on these enzymes was limited to gene expression analysis, and so far proteolytic activity has been shown only for At1-MMP. We expressed and purified the catalytic domains of all five At-MMPs as His-tagged proteins in Escherichia coli cells to delineate the biochemical differences and similarities among the Arabidopsis MMP family members. We demonstrate that all five recombinant At-MMPs are active proteases with distinct preferences for different protease substrates. Furthermore, we performed a family-wide characterization of their biochemical properties and highlight similarities and differences in their cleavage site specificities as well as pH- and temperature-dependent activities. Detailed analysis of their sequence specificity using PICS (proteomic identification of protease cleavage sites) revealed profiles similar to human MMPs with the exception of At5-MMP homology models of the At-MMP catalytic domains supported these results. Our results suggest that each At-MMP may be involved in different proteolytic processes during plant growth and development.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.TPLANTS.2018.11.010
Abstract: The rapid accumulation of plastic waste is driving international demand for renewable plastics with superior qualities (e.g., full biodegradability to CO
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.BBABIO.2015.11.011
Abstract: In the family of chlorophyll binding proteins, single helix small CAB-like proteins (SCPs) are found in all organisms performing oxygenic photosynthesis. Here, we investigated the function of these stress-inducible proteins in the cyanobacterium Synechocystis sp. PCC 6803. We compared physiological, proteome and transcriptome traits of a Photosystem I (PSI) deletion strain, which constitutively induces SCPs, and a PSI-less/ScpABCDE(-) without SCPs. The SCP mutant cells were larger in size, showed irregular thylakoid structure and differed in cell-surface morphology. Deletion of scp genes strongly affected the carbon (C) and nitrogen (N) balance, resulting in accumulation of carbohydrates and a decrease in N-rich compounds (proteins and chlorophyll). Data from transcriptomic and metabolomic experiments revealed a role of SCPs in the control of chlorophyll biosynthesis. Additionally, SCPs diminished formation of reactive oxygen species, thereby preventing damage within Photosystem II. We conclude that the lack of SCP-function to remove free chlorophyll under stress conditions has a large impact on the metabolism of the entire cell.
Publisher: Springer Science and Business Media LLC
Date: 10-2008
DOI: 10.1007/S11120-008-9368-0
Abstract: The large family of light-harvesting-like proteins contains members with one to four membrane spanning helices with significant homology to the chlorophyll a/b-binding antenna proteins of plants. From structural as well as evolutionary perspective, it is likely that the members of this family bind chlorophylls and carotenoids. However, undisputable evidence is still lacking. The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of LHCII (LHCIIb) including the chlorophyll-binding motifs. They have been proposed to act as chlorophyll-carrier proteins. Here, we analyze the in vivo absorption spectra of single scp deletion mutants in Synechocystis sp. PCC 6803 and compare the in vitro pigment binding ability of the SCP pairs ScpC/D and ScpB/E with the one of LHCII and a synthetic peptide containing the chlorophyll-binding motif (Eggink LL, Hoober JK (2000) J Biol Chem 275:9087-9090). We demonstrate that deletion of scpB alters the pigmentation in the cyanobacterial cell. Furthermore, we are able to show that chlorophylls and carotenoids interact in vitro with the pairs of ScpC/D and ScpB/E, demonstrated by fluorescence resonance energy transfer and circular dichroism.
Publisher: Springer Science and Business Media LLC
Date: 03-10-2007
DOI: 10.1007/S11120-007-9244-3
Abstract: The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267-276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA.
Publisher: Elsevier BV
Date: 2007
No related grants have been discovered for Christiane Funk.