Acclimation to the growth temperature and thermosensitivity of photosystem II in a mesophilic cyanobacterium, Synechocystis sp

Differences in the temperature dependence and thermosensitivities of PSII activities in Synechocystis sp. PCC6803 grown at 25 and 358C were studied. Hill reactions in cells, thylakoid membranes and purified PSII core complexes were measured at high temperatures or at their growth temperatures after high-temperature treatments. In the presence of 2,5-dichloro-p-benzoquinone as an electron acceptor, which can accept electrons directly from QA, the temperature dependence of the oxygen-evolving activity was almost the same in thylakoid membranes and in the purified PSII complexes from cells grown at 25 or 358C. When duroquinone, which accepts electrons only through QB plastoquinone, was used as an electron acceptor, the temperature dependence was the same for purified PSII core complexes but was different between thylakoids isolate