Abstract
Phosphatidylglycerol (PG) is the only phospholipid in thylakoid membranes, which are the site of primary processes of photosynthesis. We previously isolated a pgsA mutant of Synechocystis sp. PCC6803 defective in biosynthesis of PG. With the mutant we demonstrated that PG plays important roles in electron transport in photosystem II (PS II).
In this study, we have characterized PSII complex purified from the mutant to investigate the function of PG in PSII complex. The PSII complex of the mutant possessed about 40% oxygen-evolving activity compared to that of wild type. It was also found that extrinsic proteins were dissociated from the PSII core complex of the mutant accompanied with the release of manganese. However, PsbO bound again to the PSII core complex when the mutant cells were incubated with PG. These results demonstrate that PG is required for the binding of extrinsic proteins to sustain functional Mn-cluster in PSII complex.
