title: Moderate Heat Stress Stimulates Repair of Photosystem II During Photoinhibition in Synechocystis sp. PCC 6803.
abstract: Examination of the effects of high temperature on the photoinhibition of photosystem II (PSII) in the cyanobacterium Synechocystis sp. PCC 6803 revealed that the extent of photoinhibition of PSII was lower at moderately high temperatures (35-42 °C) than at 30 °C. Photodamage to PSII, as determined in the presence of chloramphenicol, which blocks the repair of PSII, was accelerated at the moderately high temperatures but the effects of repair were greater than those of photodamage. The synthesis de novo of the D1 protein, which is essential for the repair of PSII, was enhanced at 38 °C. Electron transport and the synthesis of ATP were also enhanced at 38 °C, while levels of reactive oxygen species fell. Inhibition of the Calvin-Benson cycle with glycolaldehyde abolished the enhancement of repair of PSII at 38 °C, suggesting that an increase in the activity of the Calvin-Benson cycle might be required for the enhancement of repair at moderately high temperatures. The synthesis de novo of metabolic intermediates of the Calvin-Benson cycle, such as 3-phosphoglycerate, was also enhanced at 38 °C. We propose that moderate heat stress might enhance the repair of PSII by stimulating the synthesis of ATP and depressing the production of reactive oxygen species, via the stimulation of electron transport and suppression of the accumulation of excess electrons on the acceptor side of photosystem I, which might be driven by an increase in the activity of the Calvin-Benson cycle.
authors: Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
authors: Mamoru
authors: M
authors: Ueno
authors: Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
authors: Penporn
authors: P
authors: Sae-Tang
authors: Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
authors: Yuri
authors: Y
authors: Kusama
authors: Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.|Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
authors: Yukako
authors: Y
authors: Hihara
authors: Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
authors: Mami
authors: M
authors: Matsuda
authors: Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
authors: Tomohisa
authors: T
authors: Hasunuma
authors: Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan nishiyama@molbiol.saitama-u.ac.jp.|Institute for Environmental Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
authors: Yoshitaka
authors: Y
authors: Nishiyama
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D004579:Electron Transport / Q000528:radiation effects; D018869:Heat-Shock Response / Q000528:radiation effects*; D042541:Intracellular Space / Q000378:metabolism; D008027:Light; D055442:Metabolome / Q000528:radiation effects; D010788:Photosynthesis / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D046939:Synechocystis / Q000378:metabolism* / Q000528:radiation effects*; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate
keywords: ATP synthesis; High temperature; Photoinhibition; Photosystem II; Reactive oxygen species; Repair