Post-transcriptional steps involved in the assembly of photosystem I in <i>Chlamydomonas</i>

Rochaix, Jean‐David; Perron, Karl; Dauvillée, David; Laroche, Fabrice; Takahashi, Yuichiro; Goldschmidt-Clermont, Michel

doi:10.1042/bst0320567

Cited by 20 publications

(12 citation statements)

References 23 publications

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“…The biosynthesis of the plant PSI complex depends on the coordinated expression of nuclear and plastid genes, the targeting of the subunits to their proper location within the chloroplast, the incorporation of the pigments and redox cofactors, and the correct assembly of the subunits to form a functionally active complex (18,19). Additional gene products have been identified by mutational analyses that may act as regulatory or scaffold proteins in the assembly of PSI.…”

Section: Photosystem I (Psi)mentioning

confidence: 99%

“…The conserved chloroplast open reading frames Ycf3, Ycf4, and Ycf37 along with specific cyanobacterial proteins like BtpA and RubA appear to be involved in posttranslational steps of PSI assembly. Ycf3 was shown to interact with PsaA and PsaD (20), whereas Ycf4 is associated with a high molecular mass complex containing several PSI subunits (19). Ycf3 as well as ycf4 mutants from Chlamydomonas lack PSI complexes (21).…”

Section: Photosystem I (Psi)mentioning

confidence: 99%

“…PsaK in plants seems to be involved in the binding of light-harvesting complex I and in mediating state transitions (14 -16), whereas in Synechocystis sp. PCC 6803 (hereafter Synechocystis 6803) it was shown that one of the two existing PsaK variants functions in high light acclimation (17).The biosynthesis of the plant PSI complex depends on the coordinated expression of nuclear and plastid genes, the targeting of the subunits to their proper location within the chloroplast, the incorporation of the pigments and redox cofactors, and the correct assembly of the subunits to form a functionally active complex (18,19). Additional gene products have been identified by mutational analyses that may act as regulatory or scaffold proteins in the assembly of PSI.…”

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confidence: 99%

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Late Assembly Steps and Dynamics of the Cyanobacterial Photosystem I

Dühring

Ossenbühl

Wilde

2007

Journal of Biological Chemistry

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The dynamics of photosystem I assembly in cyanobacteria have been addressed using in vivo pulse-chase labeling of Synechocystis sp. PCC 6803 proteins in combination with blue native polyacrylamide gel electrophoresis. The analyses indicate the existence of three different monomeric photosystem I complexes and also the high stability of photosystem I trimers. We show that in addition to a complete photosystem I monomer, containing all 11 subunits, we detected a PsaK-less monomer and a short-lived PsaL/PsaK-less complex. The latter two monomers were missing in the ycf37 mutant of Synechocystis sp. PCC 6803 that accumulates also less trimers. Pulse-chase experiments suggest that the three monomeric complexes have different functions in the biogenesis of the trimer. Based on these findings we propose a model where PsaK is incorporated in the latest step of photosystem I assembly. The PsaK-less photosystem I monomer may represent an intermediate complex that is important for the exchange of the two PsaK variants during high light acclimation. Implications of the presented data with respect to Ycf37 function are discussed. Photosystem I (PSI)2 is a multisubunit pigment-protein complex of oxygenic photosynthesis located in the thylakoid membrane of chloroplasts and cyanobacteria. Its main function is the light-dependent electron transfer from plastocyanin or cytochrome c 6 on the lumenal side to ferredoxin on the cytoplasmic or (in chloroplasts) on the stromal side of photosynthetic membranes. The crystal structures for cyanobacterial and plant PSI at 2.5 Å (1) and 4.4 Å (2) resolution have improved the understanding of the function of this complex. The PSI subunits are designated PsaA-P, according to the corresponding psaA-P genes (3-6). Their primary structures are well conserved among eukaryotes and prokaryotes performing oxygenic photosynthesis with the exception of five subunits not present in cyanobacteria (PsaG, PsaH, PsaN, PsaO, and PsaP) and one subunit PsaM, which has not been detected in plant PSI preparations. A heterodimer of two integral membrane proteins, PsaA and PsaB, forms the core of the PSI reaction center, which binds the electron transfer components P700, A 0 , A 1 , and F X . The terminal electron acceptors of PSI, the [4Fe-4S] centers F A and F B are bound to PsaC. PsaD and PsaE form, together with PsaC, peripheral ridges on the cytoplasmic and the stromal side, respectively, that provides a ferredoxin-docking site (7,8). PsaD is also required for the stable integration of PsaC, PsaL, and PsaE into the PSI complex (9). PsaE is a structural component involved in ferredoxin reduction and cyclic electron flow around PSI. PsaF is exposed to the lumenal side of the thylakoids. It functions as a plastocyanin, or in cyanobacteria cytochrome c 6 , docking site of PSI and is required for efficient electron transfer from these proteins to P700 ϩ (10, 11). PsaL is a subunit that forms most of the contacts between the monomers to form a trimer in cyanobacteria (12, 13). In contrast to cyanobacteria, trimeri...

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Section: Photosystem I (Psi)mentioning

confidence: 99%

Section: Photosystem I (Psi)mentioning

confidence: 99%

mentioning

confidence: 99%

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Late Assembly Steps and Dynamics of the Cyanobacterial Photosystem I

Dühring

Ossenbühl

Wilde

2007

Journal of Biological Chemistry

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“…Studies performed over the past several years have indicated that these factors are important for RNA stability, splicing, and initiation of translation (68,69). TAB2, for example, is required for the synthesis of the chloroplast-encoded photosystem I reaction center polypeptides, PsaB.…”

Section: Html)mentioning

confidence: 99%

Anaerobic Acclimation in Chlamydomonas reinhardtii

Mus

Dubini

Seibert

et al. 2007

Journal of Biological Chemistry

282

156

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Both prokaryotic and eukaryotic photosynthetic microbes experience conditions of anoxia, especially during the night when photosynthetic activity ceases. In Chlamydomonas reinhardtii, dark anoxia is characterized by the activation of an extensive set of fermentation pathways that act in concert to provide cellular energy, while limiting the accumulation of potentially toxic fermentative products. Metabolite analyses, quantitative PCR, and high density Chlamydomonas DNA microarrays were used to monitor changes in metabolite accumulation and gene expression during acclimation of the cells to anoxia. Elevated levels of transcripts encoding proteins associated with the production of H 2 , organic acids, and ethanol were observed in congruence with the accumulation of fermentation products. The levels of over 500 transcripts increased significantly during acclimation of the cells to anoxic conditions. Among these were transcripts encoding transcription/translation regulators, prolyl hydroxylases, hybrid cluster proteins, proteases, transhydrogenase, catalase, and several putative proteins of unknown function. Overall, this study uses metabolite, genomic, and transcriptome data to provide genome-wide insights into the regulation of the complex metabolic networks utilized by Chlamydomonas under the anaerobic conditions associated with H 2 production.

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“…They form a molecular framework which is involved in regulatory events on most hierarchical levels during plastid-gene expression including transcription, RNA metabolism/maturation and translation (for an overview see Allison 2000; Barkan and GoldschmidtClermont 2000;Manuell et al 2004;Herrin and Nickelsen 2004;Rochaix et al 2004;Nickelsen 2003 and references herein). While the cloning of regulatory factors is progressing, the different rate-limiting steps during the expression of various chloroplast genes are still poorly defined.…”

Section: Introductionmentioning

confidence: 99%

Relationship between mRNA levels and protein accumulation in a chloroplast promoter-mutant of Chlamydomonas reinhardtii

et al. 2005

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The photosynthetic chloroplast mutant G64 of Chlamydomonas reinhardtii was shown to contain a single point mutation within the 5' region of the psbD gene encoding the D2 protein of the photosystem II reaction center. The mutation affects the sequence element TATAATAT which has previously been hypothesized to function as the psbD promoter. Run-on analysis confirmed that transcription of psbD in the mutant was reduced to approximately 10% of the wild-type level. However, psbD mRNA accumulated to approximately 35%, despite the prominent decrease in RNA synthesis. This suggests that RNA-stabilization effects can compensate to some extent for a reduction in transcriptional activity. Interestingly, a direct correlation between transcript levels and the accumulation of the psbD gene product, the D2-protein, was observed in G64. The data suggest that posttranscriptionally acting regulatory factors determine the rate-limiting steps of chloroplast psbD gene expression.

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Post-transcriptional steps involved in the assembly of photosystem I in Chlamydomonas

Cited by 20 publications

References 23 publications

Late Assembly Steps and Dynamics of the Cyanobacterial Photosystem I

Late Assembly Steps and Dynamics of the Cyanobacterial Photosystem I

Anaerobic Acclimation in Chlamydomonas reinhardtii

Relationship between mRNA levels and protein accumulation in a chloroplast promoter-mutant of Chlamydomonas reinhardtii

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