Thermoluminescence and flash-oxygen characterization of the IC2 deletion mutant of Synechocystis sp. PCC 6803 lacking the Photosystem II 33 kDa protein

摘要: Abstract The psbO gene product of Photosystem II (PS II), the so-called 33 kDa extrinsic protein, is believed to be closely associated with catalytic Mn cluster responsible for light-induced water oxidation. However, this protein not absolutely required water-splitting and its precise role remains clarified. We have used flash-induced thermoluminescence oxygen evolution measurements characterize process oxidation in IC2 mutant Synechocystis sp. PCC 6803 from which had been deleted by Mayes et al. (Mayes, S.R., Cook, K.M., Self, S.J., Zhang, Z. Barber J, (1991) Biochim. Biophys. Acta 1060, 1–12). results show that extent charge stabilization S 2 Q A B states reduced about 25–30% observed wild-type, suggesting functional occurs a proportion -less cells. stability , but pair markedly increased mutant. This points structural change PS reaction center complex absence affects redox properties acceptors different extent. oscillation band, arising 3 recombinations, largely dampened indicates ability water-oxidizing reach higher states, 4 limited when absent. In agreement results, shows decreased yield pattern These indicate although an absolute requirement disturbs cycling retards formation states. rapid loss intensity during strong illumination mutated organism confirms high susceptibility photoinhibition. effect most likely consequence rate electron donation centre where accumulation highly oxidizing species may damage their pigment surroundings.