Influence of the Redox Potential of the Primary Quinone Electron Acceptor on Photoinhibition in Photosystem II

• DOI: 10.1074/jbc.m610951200
• Publication Date: 2007-02-28T02:54:48Z
• Authors: Christian Fufezan; Christine M. Gross; Martin Sjödin; A. William Ruther...; Anja Krieger-Liszkay; Diana Kirilovsky
• Keywords: Photoinhibition; P700; Oxygen evolution; Electron acceptor

We report the characterization of effects A249S mutation located within binding pocket primary quinone electron acceptor, Q(A), in D2 subunit photosystem II Thermosynechococcus elongatus. This shifts redox potential Q(A) by approximately -60 mV. mutant provides an opportunity to test hypothesis, proposed earlier from herbicide-induced effects, that photoinhibition (light-induced damage photosynthetic apparatus) is modulated Q(A). Thus influence on was investigated vivo and vitro. Compared with wild-type, showed accelerated increase singlet oxygen production. Measurements thermoluminescence fluorescence yield decay kinetics indicated charge-separated state involving destabilized mutant. These findings support hypothesis a decrease causes oxygen-mediated favoring back-reaction route involves formation reaction center chlorophyll triplet. The charge recombination are interpreted terms dynamic structural heterogeneity results high low forms effect seems reflect shift equilibrium form.