A redox-active FKBP-type immunophilin functions in accumulation of the photosystem II supercomplex in
            <i>Arabidopsis thaliana</i>

Lima, Amparo; Lima, Santiago; Wong, Joshua; Phillips, Robert S.; Buchanan, Bob B.; Luan, Sheng

doi:10.1073/pnas.0605452103

Cited by 116 publications

(110 citation statements)

References 37 publications

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“…The presence of such a large number of immunophilins with protein-folding capability suggests that these enzymes play a central role in the assembly and maintenance of protein complexes, such as the two photosystems whose subunits reside in or at least contact the thylakoid lumen. This possibility has been strengthened by a recent study showing a requirement for one of the FKBPs, 20-2, for the maintenance of PSII (13). The present study shows that a member of the other immunophilin family in the thylakoid lumen, a CYP, is essential for assembling and stabilizing PSII.…”

mentioning

confidence: 61%

A chloroplast cyclophilin functions in the assembly and maintenance of photosystem II in Arabidopsis thaliana

Cho

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Photosynthetic light reactions rely on the proper function of large protein complexes (including photosystems I and II) that reside in the thylakoid membrane. Although their composition, structure, and function are known, the repertoire of assembly and maintenance factors is still being determined. Here we show that an immunophilin of the cyclophilin type, CYP38, plays a critical role in the assembly and maintenance of photosystem II (PSII) supercomplexes (SCs) in Arabidopsis. Mutant plants with the CYP38 gene interrupted by T-DNA insertion showed stunted growth and were hypersensitive to high light. Leaf chlorophyll fluorescence analysis and thylakoid membrane composition indicated that cyp38 mutant plants had defects in PSII SCs. Sucrose supplementation enabled the rescue of the mutant phenotype under low-light conditions, but failed to mitigate hypersensitivity to high-light stress. Protein radiolabeling assays showed that, although individual thylakoid proteins were synthesized equally in mutant and wild type, the assembly of the PSII SC was impaired in the mutant. In addition, the D1 and D2 components of the mutant PSII had a short half-life under high-light stress. The results provide evidence that CYP38 is necessary for the assembly and stabilization of PSII.thylakoid lumen ͉ immunophilin ͉ photosynthesis ͉ protein folding ͉ chaperone T he light reactions and attendant evolution of oxygen in photosynthesis are carried out by four multisubunit protein complexes residing in the chloroplast thylakoid membranes: photosystems I (PSI) and II (PSII), cytochrome b 6 f complex, and CF O -CF 1 complex (1-3). For a complete understanding of the photosynthetic process, it is essential to understand the biogenesis and maintenance of the participating complexes. Earlier studies on thylakoid protein supercomplex (SC) assembly, especially PSII, concentrated on the role of stromal factors, such as the translation and import machinery (4), because only a limited number of proteins were known to reside in the thylakoid lumen. However, recent proteomic findings suggest a population of 80-100 proteins in that compartment (5-7). The immunophilin family is one of the predominant groups identified.Immunophilins were originally discovered in their capacity as cellular receptors for immunosuppressive drugs: cyclosporin A and FK506 (8, 9). The receptors for cyclosporin A and FK506, named cyclophilins (CYPs) and FK506-binding proteins (FKBPs), respectively, were collectively designated as immunophilins. A common feature of most immunophilins is the associated peptidyl-prolyl cis-trans isomerase activity that catalyzes the cis-trans conversion of X-Pro peptide bonds, a rate-limiting step in protein folding (8). These proteins are now known to occur widely in organisms ranging from bacteria and fungi to animals and plants. Studies in animal and plant systems have uncovered diverse functions of immunophilins, such as protein foldases, chaperones, and scaffolding facilitators. They also possibly have unknown catalytic capabilities (10, ...

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mentioning

confidence: 61%

A chloroplast cyclophilin functions in the assembly and maintenance of photosystem II in Arabidopsis thaliana

Cho

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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154

144

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“…LPA2 is only present in plants and absent in Chlamydomonas and cyanobacteria, suggesting that it evolved after the divergence of the land plant lineage or that it was lost in the other lineages. FKBP-2, a lumen-localized immunophilin, appears to play a role in the formation of PSII supercomplexes as in its absence the levels of PSII monomers and dimers are increased whereas accumulation of PSII supercomplexes is diminished (Lima et al, 2006). Thus a large number of factors participate in the assembly of a functional PSII complex.…”

Section: Psii Assembly Degradation and Repairmentioning

confidence: 99%

Assembly of the Photosynthetic Apparatus

Rochaix

2011

Plant Physiology

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The primary reactions of photosynthesis are mediated by three protein complexes embedded in the thylakoid membranes of chloroplasts. These complexes are PSII, the cytochrome b 6 f complex (Cytb 6 f), and PSI, which are connected in series through the photosynthetic electron transport chain. Light energy captured by the light-harvesting systems of PSII (LHCII) and PSI (LHCI) is transferred to the reaction center chlorophylls to create a charge separation across the membrane. This leads to the formation of a strong oxidant on the donor side of PSII capable of splitting water into molecular oxygen, protons, and electrons. The electrons are transferred stepwise from PSII to the plastoquinone pool, Cytb 6 f, plastocyanin, and PSI where a second charge separation creates a strong reductant capable of reducing ferredoxin that subsequently reduces NADP + to NADPH. Besides this linear electron pathway there is a cyclic pathway in which electrons are cycled around PSI through the Cytb 6 f complex. The electron transfer reactions are coupled to proton pumping into the lumen space of the thylakoids and the resulting pH gradient drives the ATP synthase for ATP production. Ultimately NADPH and ATP are used for CO 2 assimilation by the Calvin-Benson cycle. Thylakoid membranes of land plants are organized in two domains, the grana stacks, comprising 80% of the membrane, and the stromal nonappressed membranes that connect different grana stacks. The photosynthetic complexes with exception of Cytb 6 f, are not distributed evenly through the thylakoid membrane system. Whereas PSII is mostly confined to the grana regions, PSI and ATP synthase are located in the stroma lamellae. Electron transfer between these complexes is mediated by the diffusible electron carriers plastoquinone and plastocyanin.A characteristic feature of the photosynthetic complexes is that they all consist of numerous chloroplast and nucleus-encoded subunits. In the case of PSII, PSI, and Cytb 6 f these complexes contain in addition pigments such as chlorophylls and xanthophylls as well as hemes, quinones, and iron-sulfur (Fe-S) centers that act as redox cofactors. Hence the biogenesis of the photosynthetic apparatus involves a concerted interplay between the chloroplast and nucleocytosolic genetic systems as well as a tight coordination between protein and pigment synthesis and insertion into the thylakoid membranes. Analysis of numerous mutants affected in photosynthetic activity in Chlamydomonas reinhardtii, Arabidopsis (Arabidopsis thaliana), and Zea mays has provided many new insights into the assembly of the photosynthetic complexes (Barkan and Goldschmidt-Clermont, 2000;Eberhard et al., 2008).A remarkable feature of photosynthetic organisms is their ability to adapt to changing light conditions, which is reflected in changes in the organization of the photosynthetic complexes. This Update reviews recent advances in our understanding of the assembly of these complexes and for some of them, their remodeling and/or reversible association into supercomplexes...

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“…Peptidylprolyl isomerases act on protein imide bonds and are believed to coordinate protein folding, signal transduction, trafficking, assembly, and cell cycle regulation (Göthel and Marahiel, 1999). Interestingly, a member of this family has been shown to specifically modulate PSII complex formation (Lima et al, 2006) and the hypersalinity observed decrease could be associated with PSII FCP assembly changes.…”

Section: General Stress Response Proteinsmentioning

confidence: 99%

Proteomic Analysis of a Sea-Ice Diatom: Salinity Acclimation Provides New Insight into the Dimethylsulfoniopropionate Production Pathway

et al. 2011

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Dimethylsulfoniopropionate (DMSP) plays important roles in oceanic carbon and sulfur cycling and may significantly impact climate. It is a biomolecule synthesized from the methionine (Met) pathway and proposed to serve various physiological functions to aid in environmental stress adaptation through its compatible solute, cryoprotectant, and antioxidant properties. Yet, the enzymes and mechanisms regulating DMSP production are poorly understood. This study utilized a proteomics approach to investigate protein changes associated with salinity-induced DMSP increases in the model sea-ice diatom Fragilariopsis cylindrus (CCMP 1102). We hypothesized proteins associated with the Met-DMSP biosynthesis pathway would increase in relative abundance when challenged with elevated salinity. To test this hypothesis axenic log-phase cultures initially grown at a salinity of 35 were gradually shifted to a final salinity of 70 over a 24-h period. Intracellular DMSP was measured and two-dimensional gel electrophoresis was used to identify protein changes at 48 h after the shift. Intracellular DMSP increased by approximately 85% in the hypersaline cultures. One-third of the proteins increased under high salinity were associated with amino acid pathways. Three protein isoforms of S-adenosylhomo-cysteine hydrolase, which synthesizes a Met precursor, increased 1.8-to 2.1-fold, two isoforms of S-adenosyl Met synthetase increased 1.9-to 2.5-fold, and S-adenosyl Met methyltransferase increased by 2.8-fold, suggesting active methyl cycle proteins are recruited in the synthesis of DMSP. Proteins from the four enzyme classes of the proposed algal Met transaminase DMSP pathway were among the elevated proteins, supporting our hypothesis and providing candidate genes for future characterization studies.

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A redox-active FKBP-type immunophilin functions in accumulation of the photosystem II supercomplex in Arabidopsis thaliana

Cited by 116 publications

References 37 publications

A chloroplast cyclophilin functions in the assembly and maintenance of photosystem II in Arabidopsis thaliana

A chloroplast cyclophilin functions in the assembly and maintenance of photosystem II in Arabidopsis thaliana

Assembly of the Photosynthetic Apparatus

Proteomic Analysis of a Sea-Ice Diatom: Salinity Acclimation Provides New Insight into the Dimethylsulfoniopropionate Production Pathway

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