Abstract
Reactive oxygen species (ROS) inhibit the synthesis de novo of proteins that are required for the repair of photosystem II (PSII). To alter the sensitivity of the repair system to ROS, we constructed mutants of the cyanobacterium Synechococcus sp. PCC 7942 that overexpressed ROS-scavenging enzymes. Overexpression of catalase from Vibrio rumoiensis increased the tolerance of the photoautotrophic growth of cells to H2O2. In this mutant, the PSII activity became more tolerant to strong light in the presence of H2O2 than that in wild type. In vivo labeling of proteins revealed that the synthesis of the D1 protein de novo was enhanced under the oxidative conditions. Overexpression of superoxide dismutase from Synechocystis sp. PCC 6803 increased the tolerance of the photoautotrophic growth of cells to the superoxide radical generated by the presence of methyl viologen.
