Abstract
Oxidative stress inhibits the synthesis de novo of proteins that are required for the repair of photosystem II in the elongation step of translation. To investigate in vitro the mechanisms whereby ROS inhibit translational elongation, we prepared an in vitro translation system from Synechocystis sp. PCC 6803. The in vitro translation of the D1 protein was arrested in the presence of H2O2. However, addition of the reduced form of elongation factor G (EF-G), which is known to be particularly sensitive to ROS, was able to rescue the arrest of translation. Furthermore, overexpression of EF-G in Synechococcus sp. PCC 7942 increased the tolerance of cells to H2O2. Thus, EF-G might be a primary target of inhibition by ROS in the translational machinery. Interaction of EF-G with thioredoxin suggests that the redox state of EF-G might regulate the translational machinery.
