title: Quality control of photosystem II: reactive oxygen species are responsible for the damage to photosystem II under moderate heat stress.
abstract: Moderate heat stress (40 degrees C for 30 min) on spinach thylakoid membranes induced cleavage of the reaction center-binding D1 protein of photosystem II, aggregation of the D1 protein with the neighboring polypeptides D2 and CP43, and release of three extrinsic proteins, PsbO, -P, and -Q. These heat-induced events were suppressed under anaerobic conditions or by the addition of sodium ascorbate, a general scavenger of reactive oxygen species. In accordance with this, singlet oxygen and hydroxyl radicals were detected in spinach photosystem II membranes incubated at 40 degrees C for 30 min with electron paramagnetic resonance spin-trapping spectroscopy. The moderate heat stress also induced significant lipid peroxidation under aerobic conditions. We suggest that the reactive oxygen species are generated by heat-induced inactivation of a water-oxidizing manganese complex and through lipid peroxidation. Although occurring in the dark, the damages caused by the moderate heat stress to photosystem II are quite similar to those induced by excessive illumination where reactive oxygen species are involved.
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
authors.forename: Amu
authors.initials: A
authors.lastname: Yamashita
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Nijo
authors.forename: Pavel
authors.initials: P
authors.lastname: Pospísil
authors.forename: Noriko
authors.initials: N
authors.lastname: Morita
authors.forename: Daichi
authors.initials: D
authors.lastname: Takenaka
authors.forename: Ryota
authors.initials: R
authors.lastname: Aminaka
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Yasusi
authors.initials: Y
authors.lastname: Yamamoto
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000737:chemistry; D008027:Light; D015227:Lipid Peroxidation; D008954:Models, Biological; D010100:Oxygen / Q000737:chemistry; D045332:Photosystem II Protein Complex / Q000502:physiology*; D011506:Proteins / Q000737:chemistry; D017382:Reactive Oxygen Species; D018724:Spinacia oleracea / Q000378:metabolism; D013696:Temperature; D020524:Thylakoids / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D045332:Photosystem II Protein Complex; D011506:Proteins; D017382:Reactive Oxygen Species; D014867:Water; D006861:Hydrogen Peroxide; D010100:Oxygen