Quality control of Photosystem II: Cleavage and aggregation of heat-damaged D1 protein in spinach thylakoids |
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Authors: | Keisuke Komayama Daichi Takenaka Amu Yamashita Yohsuke Nakayama Satoshi Ohira Maya Velitchkova Yasusi Yamamoto |
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Affiliation: | a Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan b Institute of Biophysics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria c Department of Biology, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan |
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Abstract: | Moderate heat stress (40 °C, 30 min) on spinach thylakoids induced cleavage of the D1 protein, producing an N-terminal 23-kDa fragment, a C-terminal 9-kDa fragment, and aggregation of the D1 protein. A homologue of Arabidopsis FtsH2 protease, which is responsible for degradation of the damaged D1 protein, was abundant in the stroma thylakoids. Two processes occurred in the thylakoids in response to heat stress: dephosphorylation of the D1 protein in the stroma thylakoids, and aggregation of the phosphorylated D1 protein in the grana. Heat stress also induced the release of the extrinsic PsbO, P and Q proteins from Photosystem II, which affected D1 degradation and aggregation significantly. The cleavage and aggregation of the D1 protein appear to be two alternative processes influenced by protein phosphorylation/dephosphorylation, distribution of FtsH, and intactness of the thylakoids. |
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Keywords: | PSII, Photosystem II D1 and D2, reaction center binding proteins of PSII FtsH, filamentation temperature sensitive H MALDI-TOF, matrix-assisted laser desorption/ionization-time of flight QB, secondary plastoquinone electron acceptor CP43, the antenna chlorophyll-binding protein of PSII with a relative molecular mass of 43  kDa PsbO, P and Q, the extrinsic proteins of PSII involved in the regulation of oxygen evolution HTG, n-heptyl-β- smallcaps" >d-thioglucoside Tricine, N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine PAGE, polyacrylamide gel electrophoresis p-Thr, phosphothreonine ECL, enhanced chemiluminescence LHCII, the light-harvesting chlorophyll-protein complex associated with PSII Mr, relative molecular mass |
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