Role of chloride ion in hydroxyl radical production in photosystem II under heat stress: Electron paramagnetic resonance spin-trapping study
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Hydroxyl radical (HO•) production in photosystem II (PSII) was studied by electron paramagnetic resonance (EPR) spin-trapping technique. It is demonstrated here that the exposure of PSII membranes to heat stress (40 °C) results in HO• formation, as monitored by the formation of EMPO-OH adduct EPR signal. The presence of different exogenous halides significantly suppressed the EMPO-OH adduct EPR signal in PSII membranes under heat stress. The addition of exogenous acetate and blocker of chloride channel suppressed the EMPO-OH adduct EPR signal, whereas the blocker of calcium channel did not affect the EMPO-OH adduct EPR signal. Heat-induced hydrogen peroxide (H2O2) production was studied by amplex red fluorescent assay. The presence of exogenous halides, acetate and chloride blocker showed the suppression of H2O2 production in PSII membranes under heat stress. Based on our results, it is proposed that the formation of HO• under heat stress is linked to uncontrolled accessibility of water to the water-splitting manganese complex caused by the release of chloride ion on the electron donor side of PSII. Uncontrolled water accessibility to the water-splitting manganese complex causes the formation of H2O2 due to improper water oxidation, which leads to the formation of HO• via the Fenton reaction under heat stress.
KeywordsPhotosystem II Electron paramagnetic resonance Hydroxyl radical Spin trap Heat stress Chloride ion Hydrogen peroxide Amplex red
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- Allakhverdiev SI, Feyziev YM, Ahmed A, Hayashi H, Aliev JA, Klimov VV, Murata N, Carpentier R (1996) Stabilization of oxygen evolution and primary electron transport reactions in photosystem II against heat stress with glycinebetaine and sucrose. J Photochem Photobiol B Biol 34:149–157CrossRefGoogle Scholar
- Bukhov NG, Mohanty P (1999) Elevated temperature stress effects on photosystems: characterization and evaluation of the nature of heat induced impairments. In: Singhal GS, Renger G, Sopory SK, Irrgang K-D, Govindjee (eds) Concepts in photobiology: photosynthesis and photomorphogenesis. Narosa Publishing house, New Delhi, pp 617–648Google Scholar
- Gorkom HJV, Yocum CF (2005) The calcium and chloride cofactors. In: Wydrzynski T, Satoh K (eds) Photosystem II: the light-driven water: plastoquinone oxidoreductase. Springer, Dordrecht, pp 307–327Google Scholar
- Komayama K, Khatoon M, Takenaka D, Horie J, Yamashita A, Yoshioka M, Nakayama Y, Yoshida M, Ohira S, Morita N, Velitchkova M, Enami I, Yamamoto Y (2007) Quality control of photosystem II: cleavage and aggregation of heat-damaged D1 protein in spinach thylakoids. Biochim Biophys Acta 1767:838–846CrossRefGoogle Scholar
- Pospíšil P, Haumann M, Dittmer J, Sole VA, Dau H (2003) Stepwise transition of the tetra manganese complex of photosystem II to a binuclear Mn2(μ-O)2 complex in response to a temperature jump: a time-resolved structural investigation employing X-ray absorption spectroscopy. Biophys J 84:1370–1386CrossRefGoogle Scholar
- Weis E, Berry JS (1988) Plants and high temperature stress. In: Long SP, Noris Woodward FI (eds) Plants and temperature, the company of biologist limited. Cambridge, U.K. Woodbury, pp 329–346Google Scholar