Photoinhibition of photosystem II under environmental stress |
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Authors: | Norio Murata Shunichi Takahashi Suleyman I Allakhverdiev |
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Institution: | a National Institute for Basic Biology, Okazaki 444-8585, Japan b Molecular Plant Physiology Group, Research School of Biological Sciences, The Australian National University, Canberra ACT 0200, Australia c Cell-Free Science and Technology Research Center and Satellite Venture Business Laboratory, Ehime University, Bunkyo-cho, Matsuyama 790-8577, Japan d Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia |
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Abstract: | Inhibition of the activity of photosystem II (PSII) under strong light is referred to as photoinhibition. This phenomenon is due to an imbalance between the rate of photodamage to PSII and the rate of the repair of damaged PSII. In the “classical” scheme for the mechanism of photoinhibition, strong light induces the production of reactive oxygen species (ROS), which directly inactivate the photochemical reaction center of PSII. By contrast, in a new scheme, we propose that photodamage is initiated by the direct effect of light on the oxygen-evolving complex and that ROS inhibit the repair of photodamaged PSII by suppressing primarily the synthesis of proteins de novo. The activity of PSII is restricted by a variety of environmental stresses. The effects of environmental stress on damage to and repair of PSII can be examined separately and it appears that environmental stresses, with the exception of strong light, act primarily by inhibiting the repair of PSII. Studies have demonstrated that repair-inhibitory stresses include CO2 limitation, moderate heat, high concentrations of NaCl, and low temperature, each of which suppresses the synthesis of proteins de novo, which is required for the repair of PSII. We postulate that most types of environmental stress inhibit the fixation of CO2 with the resultant generation of ROS, which, in turn, inhibit protein synthesis. |
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Keywords: | Environmental stress Photodamage Photoinhibition Photosystem II Protein synthesis Repair |
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