title: Oxidative stress inhibits the repair of photodamage to the photosynthetic machinery.
abstract: Absorption of excess light energy by the photosynthetic machinery results in the generation of reactive oxygen species (ROS), such as H2O2. We investigated the effects in vivo of ROS to clarify the nature of the damage caused by such excess light energy to the photosynthetic machinery in the cyanobacterium Synechocystis sp. PCC 6803. Treatments of cyanobacterial cells that supposedly increased intracellular concentrations of ROS apparently stimulated the photodamage to photosystem II by inhibiting the repair of the damage to photosystem II and not by accelerating the photodamage directly. This conclusion was confirmed by the effects of the mutation of genes for H2O2-scavenging enzymes on the recovery of photosystem II. Pulse labeling experiments revealed that ROS inhibited the synthesis of proteins de novo. In particular, ROS inhibited synthesis of the D1 protein, a component of the reaction center of photosystem II. Northern and western blot analyses suggested that ROS might influence the outcome of photodamage primarily via inhibition of translation of the psbA gene, which encodes the precursor to D1 protein.
authors.affiliation: Department of Regulation Biology, National Institute for Basic Biology, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nishiyama
authors.forename: H
authors.initials: H
authors.lastname: Yamamoto
authors.forename: S I
authors.initials: SI
authors.lastname: Allakhverdiev
authors.forename: M
authors.initials: M
authors.lastname: Inaba
authors.forename: A
authors.initials: A
authors.lastname: Yokota
authors.forename: N
authors.initials: N
authors.lastname: Murata
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D015152:Blotting, Northern; D015153:Blotting, Western; D000458:Cyanobacteria / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D015964:Gene Expression Regulation, Bacterial / Q000528:radiation effects; D005798:Genes, Bacterial; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000633:toxicity; D008027:Light / Q000009:adverse effects*; D018384:Oxidative Stress; D010269:Paraquat / Q000633:toxicity; D010441:Peptide Chain Elongation, Translational / Q000528:radiation effects; D010442:Peptide Chain Initiation, Translational / Q000528:radiation effects; D010788:Photosynthesis / Q000528:radiation effects*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D045332:Photosystem II Protein Complex; D012329:RNA, Bacterial / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011838:Radiation-Sensitizing Agents / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011838:Radiation-Sensitizing Agents; D017382:Reactive Oxygen Species; C422369:photosystem II, psbA subunit; D006861:Hydrogen Peroxide; D010269:Paraquat