Molecular Mechanisms of Light Stress of Photosynthesis

Vass, Imre; Cser, Krisztián; Cheregi, Otilia

doi:10.1196/annals.1391.017

Cited by 59 publications

(39 citation statements)

References 66 publications

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“…Photooxidative damage to the photosynthetic apparatus, particularly to the reaction centers of photosystem II, is a routine and inescapable consequence of oxygenic photosynthesis (22,41) that occurs even under very-low-light conditions for Synechocystis (1). Cells of Synechocystis, as do those of other oxygenic photosynthetic organisms, have numerous ways of preventing, minimizing, and/or repairing photooxidative damage (21,22,26).…”

Section: Discussionmentioning

confidence: 99%

Inactivation of Genes Encoding Plastoglobulin-Like Proteins in Synechocystis sp. PCC 6803 Leads to a Light-Sensitive Phenotype

et al. 2010

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Plastoglobulins (PGL) are the predominant proteins of lipid globules in the plastids of flowering plants. Genes encoding proteins similar to plant PGL are also present in algae and cyanobacteria but in no other organisms, suggesting an important role for these proteins in oxygenic photosynthesis. To gain an understanding of the core and fundamental function of PGL, the two genes that encode PGL-like polypeptides in the cyanobacterium Synechocystis sp. PCC 6803 (pgl1 and pgl2) were inactivated individually and in combination. The resulting mutants were able to grow under photoautotrophic conditions, dividing at rates that were comparable to that of the wild-type (WT) under low-light (LL) conditions (10 microeinsteins ⅐ m ؊2 ⅐ s ؊1 ) but lower than that of the WT under moderately high-irradiance (HL) conditions (150 microeinsteins ⅐ m ؊2 ⅐ s ؊1 ). Under HL, each ⌬pgl mutant had less chlorophyll, a lower photosystem I (PSI)/PSII ratio, more carotenoid per unit of chlorophyll, and very much more myxoxanthophyll (a carotenoid symptomatic of high light stress) per unit of chlorophyll than the WT. Large, heterogeneous inclusion bodies were observed in cells of mutants inactivated in pgl2 or both pgl2 and pgl1 under both LL and HL conditions. The mutant inactivated in both pgl genes was especially sensitive to the light environment, with alterations in pigmentation, heterogeneous inclusion bodies, and a lower PSI/PSII ratio than the WT even for cultures grown under LL conditions. The WT cultures grown under HL contained 2-to 3-fold more PGL1 and PGL2 per cell than cultures grown under LL conditions. These and other observations led us to conclude that the PGL-like polypeptides of Synechocystis play similar but not identical roles in some process relevant to the repair of photooxidative damage.

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Section: Discussionmentioning

confidence: 99%

Inactivation of Genes Encoding Plastoglobulin-Like Proteins in Synechocystis sp. PCC 6803 Leads to a Light-Sensitive Phenotype

et al. 2010

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“…Increased rates of PSII-mediated plastoquinone reduction exceeding plastoquinol oxidation result in an increased back electron flow and charge recombination, causing damage to PSII core proteins (Keren et al, 1997;Vass et al, 2007). Only under strong illumination were PSII activity and D1 levels reduced in the Chlamydomonas mutant.…”

Section: Lack Of Psbtc Results In Increased D1 Degradationmentioning

confidence: 99%

Impact of PsbTc on Forward and Back Electron Flow, Assembly, and Phosphorylation Patterns of Photosystem II in Tobacco

et al. 2008

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Photosystem II (PSII) of oxygen-evolving cyanobacteria, algae, and land plants mediates electron transfer from the Mn 4 Ca cluster to the plastoquinone pool. It is a dimeric supramolecular complex comprising more than 30 subunits per monomer, of which 16 are bitopic or peripheral, low-molecular-weight components. Directed inactivation of the plastid gene encoding the low-molecular-weight peptide PsbTc in tobacco (Nicotiana tabacum) does not prevent photoautotrophic growth. Mutant plants appear normal green, and levels of PSII proteins are not affected. Yet, PSII-dependent electron transport, stability of PSII dimers, and assembly of PSII light-harvesting complexes (LHCII) are significantly impaired. PSII light sensitivity is moderately increased and recovery from photoinhibition is delayed, leading to faster D1 degradation in DpsbTc under high light. Thermoluminescence emission measurements revealed alterations of midpoint potentials of primary/secondary electronaccepting plastoquinone of PSII interaction. Only traces of CP43 and no D1/D2 proteins are phosphorylated, presumably due to structural changes of PSII in DpsbTc. In striking contrast to the wild type, LHCII in the mutant is phosphorylated in darkness, consistent with its association with PSI, indicating an increased pool of reduced plastoquinone in the dark. Finally, our data suggest that the secondary electron-accepting plastoquinone of PSII site, the properties of which are altered in DpsbTc, is required for oxidation of reduced plastoquinone in darkness in an oxygen-dependent manner. These data present novel aspects of plastoquinone redox regulation, chlororespiration, and redox control of LHCII phosphorylation.PSII, the oxygen-evolving pigment-protein complex of the thylakoid membrane system, is present in photosynthetic organisms from cyanobacteria to vascular plants. The proteins of the photochemically active reaction center (RC), the heterodimeric polypeptides PsbA (D1) and PsbD (D2) and the lowmolecular-weight (LMW) subunits PsbE and PsbF, and the a-and b-chains of cytochrome b 559 coordinate the redox cofactors necessary for primary PSII photochemistry. Electron flow following charge separation occurs via several electron carriers of the RC, including pheophytin a, as well as the primary and secondary quinones, Q A and Q B . The striking similarities between cyanobacterial and land plant PSII core components, including the intrinsic light-harvesting antennae, the chlorophyll-binding proteins CP43 and CP47, and their interactions during photosynthetic charge separation, suggest a high degree of structural and functional conservation. Thus, much of the information obtained from crystallization of a cyanobacterial PSII can be applied to that of higher plants (Zouni et al., 2001;Kamiya and Shen, 2003;Ferreira et al., 2004;Loll et al., 2005;Nield and Barber, 2006).Besides the RC, the PSII core contains a remarkably high number (16) of intrinsic or peripheral LMW peptides. Five of them are encoded in eukaryotes by nuclear genes (psbR, psbTn, psbW, ps...

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“…The here described system shows a significant improved operational stability. This improvement of stability can be attributed to a fast ET process between PS2 and the redox polymer and, thus, further reducing the light-induced damage of PS2, which is either caused by reactive oxygen species formed during recombination processes if ET is inefficient [20] or by damage of the oxygen-evolving manganese complex itself as discussed previously [21].…”

Section: à2mentioning

confidence: 96%

Photo‐Induced Electron Transfer Between Photosystem 2 via Cross‐linked Redox Hydrogels

et al. 2008

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Photosystem 2 (PS2) that catalyses light driven water splitting in photosynthesis was wired to electrode surfaces via osmium-containing redox polymers based on poly(vinyl)imidazol. The redox polymer hydrogel worked as both immobilization matrix and electron acceptor for the enzyme. Upon illumination, the enzymatic reaction could be switched on and a catalytic current was observed at the electrode. The catalytic current is directly dependent on the intensity of light used for the excitation of PS2. A typical current density of 45 mA cm À2 at a light intensity of 2.65 mW cm À2 could be demonstrated with a significantly improved operational stability.

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Molecular Mechanisms of Light Stress of Photosynthesis

Cited by 59 publications

References 66 publications

Inactivation of Genes Encoding Plastoglobulin-Like Proteins in Synechocystis sp. PCC 6803 Leads to a Light-Sensitive Phenotype

Inactivation of Genes Encoding Plastoglobulin-Like Proteins in Synechocystis sp. PCC 6803 Leads to a Light-Sensitive Phenotype

Impact of PsbTc on Forward and Back Electron Flow, Assembly, and Phosphorylation Patterns of Photosystem II in Tobacco

Photo‐Induced Electron Transfer Between Photosystem 2 via Cross‐linked Redox Hydrogels

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