Singlet Oxygen Inhibits the Repair of Photosystem II by Suppressing the Translation Elongation of the D1 Protein in Synechocystis sp. PCC 6803

• Published in: Biochemistry (Easton) Vol. 43; no. 35; pp. 11321 - 11330
• Main Authors: Nishiyama, Yoshitaka, Allakhverdiev, Suleyman I., Yamamoto, Hiroshi, Hayashi, Hidenori, Murata, Norio
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 07.09.2004
• Subjects: Cyanobacteria - drug effects; Cyanobacteria - genetics; Cyanobacteria - metabolism; DNA Repair - drug effects; Electron Spin Resonance Spectroscopy; Eosine Yellowish-(YS) - chemistry; Gene Expression Regulation, Bacterial - drug effects; Light - adverse effects; Peptide Chain Elongation, Translational - drug effects; Photochemistry - methods; Photosensitizing Agents - chemistry; Photosystem II Protein Complex - antagonists & inhibitors; Photosystem II Protein Complex - biosynthesis; Photosystem II Protein Complex - genetics; Photosystem II Protein Complex - metabolism; Protein Precursors - antagonists & inhibitors; Protein Precursors - biosynthesis; Protein Precursors - genetics; Protein Processing, Post-Translational - drug effects; RNA, Messenger - antagonists & inhibitors; RNA, Messenger - biosynthesis; Rose Bengal - chemistry; Singlet Oxygen - metabolism; Singlet Oxygen - toxicity; Synechocystis
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi036178q

Singlet oxygen, generated during photosynthesis, is a strong oxidant that can, potentially, damage various molecules of biological importance. We investigated the effects in vivo of singlet oxygen on the photodamage to photosystem II (PSII) in the cyanobacterium Synechocystis sp. PCC 6803. Increases in intracellular concentrations of singlet oxygen, caused by the presence of photosensitizers, such as rose bengal and ethyl eosin, stimulated the apparent photodamage to PSII. However, actual photodamage to PSII, as assessed in the presence of chloramphenicol, was unaffected by the production of singlet oxygen. These observations suggest that singlet oxygen produced by added photosensitizers acts by inhibiting the repair of photodamaged PSII. Labeling of proteins in vivo revealed that singlet oxygen inhibited the synthesis of proteins de novo and, in particular, the synthesis of the D1 protein. Northern blotting analysis indicated that the accumulation of psbA mRNAs, which encode the D1 protein, was unaffected by the production of singlet oxygen. Subcellular localization of polysomes with bound psbA mRNAs suggested that the primary target of singlet oxygen might be the elongation step of translation.