The PsbQ′ protein affects the redox potential of the QA in photosystem II
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Red alga contains four extrinsic proteins in photosystem II (PSII), which are PsbO, PsbV, PsbU, and PsbQ′. Except for the PsbQ′, the composition is the same in cyanobacterial PSII. Reconstitution analysis of cyanobacterial PSII has shown that oxygen-evolving activity does not depend on the presence of PsbQ′. Recently, the structure of red algal PSII was elucidated. However, the role of PsbQ′ remains unknown. In this study, the function of the acceptor side of PSII was analyzed in PsbQ′-reconstituted PSII by redox titration of QA and thermoluminescence. The redox potential of QA was positively shifted when PsbQ′ was attached to the PSII. The positive shift of QA is thought to cause a decrease in the amount of triplet chlorophyll in PSII. On the basis of these results, we propose that PsbQ′ has a photoprotective function when irradiated with strong light.
Additional key wordsdiversity evolution photoinhibition photosynthesis
chlorophyll protein 43 kDa
chlorophyll protein 47 kDa
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- Björn L.O.: The evolution of photosynthesis and its environmental impact.–In: Björn L.O. (ed.): Photobiology. Pp. 207–230. Springer, New York 2015.Google Scholar
- Porra R., Thompson W., Kriedemann P.: Determination of accurate extinction coefficients and simultaneous equations for assaying chlorophylls a and b extracted with four different solvents: verification of the concentration of chlorophyll standards by atomic absorption spectroscopy.–BBABioenergetics 975: 384–394, 1989.CrossRefGoogle Scholar
- Vass I., Horváth G., Herczeg T. et al.: Photosynthetic energy conservation investigated by thermoluminescence. Activation energies and half-lives of thermoluminescence bands of chloroplasts determined by mathematical resolution of glow curves.–Biochim. Biophys. Acta 634: 140–152, 1981.CrossRefPubMedGoogle Scholar