PsbT Polypeptide Is Required for Efficient Repair of Photodamaged Photosystem II Reaction Center

Ohnishi, Norikazu; Takahashi, Yuichiro

doi:10.1074/jbc.m104454200

Cited by 44 publications

(45 citation statements)

References 34 publications

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“…Only under strong illumination were PSII activity and D1 levels reduced in the Chlamydomonas mutant. In contrast to the data obtained with tobacco mutants, photosensitivity and D1 degradation in the presence of CAP were apparently not changed in the Chlamydomonas mutant, suggesting that PsbTc may not be relevant for photoprotection but may be required for an efficient recovery of photodamaged PSII in the algae (Ohnishi and Takahashi, 2001). Furthermore, PsbTc appeared to be involved in the activation of forward Q A electron flow during repair of PSII from photoinhibition in C. reinhardtii (Ohnishi et al, 2007).…”

Section: Lack Of Psbtc Results In Increased D1 Degradationcontrasting

confidence: 52%

“…Effect of PsbTc Deletion on Assembly, Stability, and Structure of PSII Studies on PsbTc deletion mutants were reported from Synechocystis 6803 (Iwai et al, 2004) and two Thermosynechococcus species (Henmi et al, 2008) representing eubacterial organisms and from Chlamydomonas reinhardtii (Monod et al, 1994;Ohnishi and Takahashi, 2001;Ohnishi et al, 2007). Data obtained with Thermosynechococcus suggested that PsbTc is involved in the assembly of dimeric PSII complexes.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Lack Of Psbtc Results In Increased D1 Degradationcontrasting

confidence: 52%

Section: Discussionmentioning

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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“…Although the in vivo dimerization of PSII in cyanobacteria has been questioned due to the use of detergents for solubilization and in vitro analysis of the thylakoid complexes (Takahashi et al, 2009;Watanabe et al, 2009), there is compelling evidence for dimer formation by mutant approaches. Indeed, small PSII subunits PsbM and PsbT, located in monomer-monomer interface, have been shown crucial for proper assembly and repair of PSII (Ohnishi and Takahashi, 2001;Iwai et al, 2004;Bentley et al, 2008). Since the Sll0218 protein is expressed only under low (i.e., air level) CO 2 conditions, we postulate that the assembly of PSII dimers differs depending on the presence or absence of the Sll0218 proteins (see below).…”

Section: Sll0218 Protein Resides In the Thylakoid Membrane And Stabilmentioning

confidence: 99%

Operon flv4-flv2 Provides Cyanobacterial Photosystem II with Flexibility of Electron Transfer

et al. 2012

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Synechocystis sp PCC 6803 has four genes encoding flavodiiron proteins (FDPs; Flv1 to Flv4). Here, we investigated the flv4-flv2 operon encoding the Flv4, Sll0218, and Flv2 proteins, which are strongly expressed under low inorganic carbon conditions (i.e., air level of CO 2 ) but become repressed at elevated CO 2 conditions. Different from FDP homodimers in anaerobic microbes, Synechocystis Flv2 and Flv4 form a heterodimer. It is located in cytoplasm but also has a high affinity to membrane in the presence of cations. Sll0218, on the contrary, resides in the thylakoid membrane in association with a high molecular mass protein complex. Sll0218 operates partially independently of Flv2/Flv4. It stabilizes the photosystem II (PSII) dimers, and according to biophysical measurements opens up a novel electron transfer pathway to the Flv2/Flv4 heterodimer from PSII. Constructed homology models suggest efficient electron transfer in heterodimeric Flv2/Flv4. It is suggested that Flv2/Flv4 binds to thylakoids in light, mediates electron transfer from PSII, and concomitantly regulates the association of phycobilisomes with PSII. The function of the flv4-flv2 operon provides many b-cyanobacteria with a so far unknown photoprotection mechanism that evolved in parallel with oxygen-evolving PSII.

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“…Chloroplast protein import assays showed that, in addition, the nuclear-encoded subunits of the water-splitting complex undergo a stepwise maturation and assembly process (Hashimoto et al, 1997). Subsequent analysis of PSII mutants in Arabidopsis that missed one or more PSII subunits refined these initial models (Ohnishi and Takahashi, 2001;Suorsa et al, 2004). Following thylakoid solubilization with nonionic detergents, various partial supercomplexes have been isolated and characterized from Arabidopsis, in particular, the complexes C2S and C2M (;880 kD), C2S2 (;1040 kD), S2SM (;1100 kD), C2S2M (1250 kD), and the full supercomplex C2S2M2 (C2S2M2) (Caffarri et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

MET1 Is a Thylakoid-Associated TPR Protein Involved in Photosystem II Supercomplex Formation and Repair in Arabidopsis

et al. 2015

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ORCID ID: 0000-0001-9536-0487 (K.J.v.W.)Photosystem II (PSII) requires constant disassembly and reassembly to accommodate replacement of the D1 protein. Here, we characterize Arabidopsis thaliana MET1, a PSII assembly factor with PDZ and TPR domains. The maize (Zea mays) MET1 homolog is enriched in mesophyll chloroplasts compared with bundle sheath chloroplasts, and MET1 mRNA and protein levels increase during leaf development concomitant with the thylakoid machinery. MET1 is conserved in C3 and C4 plants and green algae but is not found in prokaryotes. Arabidopsis MET1 is a peripheral thylakoid protein enriched in stroma lamellae and is also present in grana. Split-ubiquitin assays and coimmunoprecipitations showed interaction of MET1 with stromal loops of PSII core components CP43 and CP47. From native gels, we inferred that MET1 associates with PSII subcomplexes formed during the PSII repair cycle. When grown under fluctuating light intensities, the Arabidopsis MET1 null mutant (met1) showed conditional reduced growth, near complete blockage in PSII supercomplex formation, and concomitant increase of unassembled CP43. Growth of met1 in high light resulted in loss of PSII supercomplexes and accelerated D1 degradation. We propose that MET1 functions as a CP43/CP47 chaperone on the stromal side of the membrane during PSII assembly and repair. This function is consistent with the observed differential MET1 accumulation across dimorphic maize chloroplasts.

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PsbT Polypeptide Is Required for Efficient Repair of Photodamaged Photosystem II Reaction Center

Cited by 44 publications

References 34 publications

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

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

Operon flv4-flv2 Provides Cyanobacterial Photosystem II with Flexibility of Electron Transfer

MET1 Is a Thylakoid-Associated TPR Protein Involved in Photosystem II Supercomplex Formation and Repair in Arabidopsis

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