| 1. |
- Calderon, Robert H., et al.
(författare)
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A conserved rubredoxin is necessary for photosystem II accumulation in diverse oxygenic photoautotrophs
- 2013
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 288:37, s. 26688-26696
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Tidskriftsartikel (refereegranskat)abstract
- In oxygenic photosynthesis, two photosystems work in tandem to harvest light energy and generate NADPH and ATP. Photosystem II (PSII), the protein-pigment complex that uses light energy to catalyze the splitting of water, is assembled from its component parts in a tightly regulated process that requires a number of assembly factors. The 2pac mutant of the unicellular green alga Chlamydomonas reinhardtii was isolated and found to have no detectable PSII activity, whereas other components of the photosynthetic electron transport chain, including photosystem I, were still functional. PSII activity was fully restored by complementation with the RBD1 gene, which encodes a small iron-sulfur protein known as a rubredoxin. Phylogenetic evidence supports the hypothesis that this rubredoxin and its orthologs are unique to oxygenic phototrophs and distinct from rubredoxins in Archaea and bacteria (excluding cyanobacteria). Knockouts of the rubredoxin orthologs in the cyanobacterium Synechocystis sp. PCC 6803 and the plant Arabidopsis thaliana were also found to be specifically affected in PSII accumulation. Taken together, our data suggest that this rubredoxin is necessary for normal PSII activity in a diverse set of organisms that perform oxygenic photosynthesis.
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| 2. |
- Garcia-Cerdan, Jose G., et al.
(författare)
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The PsbW protein stabilizes the supramolecular organization of photosystem II in higher plants
- 2011
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Ingår i: The Plant Journal. - : Wiley-Blackwell. - 0960-7412 .- 1365-313X. ; 65:3, s. 368-381
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Tidskriftsartikel (refereegranskat)abstract
- PsbW, a 6.1-kDa low-molecular-weight protein, is exclusive to photosynthetic eukaryotes, and associates with the photosystem II (PSII) protein complex. In vivo and in vitro comparison of Arabidopsis thaliana wild-type plants with T-DNA insertion knock-out mutants completely lacking the PsbW protein, or with antisense inhibition plants exhibiting decreased levels of PsbW, demonstrated that the loss of PsbW destabilizes the supramolecular organization of PSII. No PSII-LHCII supercomplexes could be detected or isolated in the absence of the PsbW protein. These changes in macro-organization were accompanied by a minor decrease in the chlorophyll fluorescence parameter F-V/F-M, a strongly decreased PSII core protein phosphorylation and a modification of the redox state of the plastoquinone (PQ) pool in dark-adapted leaves. In addition, the absence of PsbW protein led to faster redox changes in the PQ pool, i.e. transitions from state 1 to state 2, as measured by changes in stationary fluorescence (F-S) kinetics, compared with the wild type. Despite these dramatic effects on macromolecular structure, the transgenic plants exhibited no significant phenotype under normal growth conditions. We suggest that the PsbW protein is located close to the minor antenna of the PSII complex, and is important for the contact and stability between several PSII-LHCII supercomplexes.
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| 3. |
- Granlund, Irene, et al.
(författare)
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The TL29 protein is lumen located, associated with PSII and not an ascorbate peroxidase
- 2009
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Ingår i: Plant and Cell Physiology. - : Oxford Journals. - 0032-0781 .- 1471-9053. ; 50:11, s. 1898-1910
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Tidskriftsartikel (refereegranskat)abstract
- The TL29 protein is one of the more abundant proteins in the thylakoid lumen of plant chloroplasts. Based on its sequence homology to ascorbate peroxidases, but without any supporting biochemical evidence, TL29 was suggested to be involved in the plant defense system against reactive oxygen species and consequently renamed to APX4. Our in vivo and in vitro analyses failed to show any peroxidase activity associated with TL29; it bound neither heme nor ascorbate. Recombinant overexpressed TL29 had no ascorbate-dependent peroxidase activity, and various mutational analyses aiming to convert TL29 into an ascorbate peroxidase failed. Furthermore, in the thylakoid lumen no such activity could be associated with TL29 and, additionally, TL29 knock-out mutants did not show any decreased peroxidase activity or increased content of radical oxygen species when grown under light stress. Instead we could show that TL29 is a lumen-located component associated with PSII.
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| 4. |
- Petersson, Ulrika A., et al.
(författare)
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The Prx Q protein of Arabidopsis thaliana is a member of the luminal chloroplast proteome
- 2006
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 580:26, s. 6055-6061
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Tidskriftsartikel (refereegranskat)abstract
- Peroxiredoxins have been discovered in many organisms ranging from eubacteria to mammals, and their known biological functions include both oxidant defense and signal transduction. The genome of Arabidopsis thaliana encodes for ten individual peroxiredoxins, of which four are located in the chloroplast. The best-characterized member of the chloroplast peroxiredoxins is 2-Cys Prx that is associated with the stroma side of the thylakoid membrane and is considered to participate in antioxidant defense and protection of photosynthesis. This study addressed the chloroplast peroxiredoxin Prx Q and showed that its subcellular location is the lumen of the thylakoid membrane. To get insight in the biological function of the Prx Q protein of Arabidopsis, the protein levels of the Prx Q protein in thylakoid membranes were studied under different light conditions and oxidative stress. A T-DNA knockout mutant of Prx Q did not show any visible phenotype and had normal photosynthetic performance with a slightly increased oxygen evolving activity.
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