Abstract
Photosystem II (PSII) is particularly sensitive to high temperature. However, the thermal stability of PSII is enhanced upon the acclimation of photosynthetic organisms to moderately high temperatures. In the present study, we studied the molecular mechanisms of the thermal acclimation of PSII in Synechocystis sp. PCC 6803. We found that the enhanced thermal stability of PSII was retained in the isolated PSII complex. Proteome analysis suggested several candidate proteins in the PSII complex with enhanced thermal stability. Screening of their knockout mutants revealed a protein responsible for the thermal stability. This protein was assigned to FabI, which is a key enzyme in fatty acid synthesis. Incubation of cells with a specific inhibitor for this enzyme prevented thermal acclimation completely. These observations suggest that synthesis de novo of lipids around the PSII complex is required for the thermal acclimation of PSII.
