Elongation factors regulate the repair of photosystem II oxido-reductively

Photoinhibition of photosystem II (PSII) limits the fixation of light energy by photosynthesis and, thus, the productivity of plants everywhere. Photosynthetic organisms are equipped with a system that protects the photosynthetic machinery from photoinhibition by enhancing the repair of photodamaged PSII. However, the repair process is inhibited by oxidative stress and other types of environmental stress, which generate reactive oxygen species (ROS), primarily via the suppression of protein synthesis. The molecular mechanism responsible for the inhibitory effects of ROS on protein synthesis is now well understood. In this review we focus on the fact that translation elongation factors EF-G and EF-Tu contain highly conserved cysteine residues that are sensitive to oxidation by ROS, and the way in which exposure to ROS results in the interruption of peptide elongation.