Deactivation processes in PsbA1-Photosystem II and PsbA3-Photosystem II under photoinhibitory conditions in the cyanobacterium Thermosynechococcus elongatus

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• 作者：Shogo Ogami^a ; Alain Boussac^b ; Miwa Sugiura^a ; ^c ; ^d ; ^{miwa.sugiura@ehime-u.ac.jp}
• 关键词：Photosystem II ; Water oxidation ; PsbA ; D1 ; Thermosynechococcus elongatus
• 刊名：Biochimica et Biophysica Acta (BBA)/Bioenergetics
• 出版年：2012
• 期刊代码：13_00052728
• 类别：bio
• 出版时间：August, 2012
• 卷：1817
• 期：8
• 页码：1322-1330
• 文件大小：1002 K

摘要

The sensitivity to high light conditions of Photosystem II with either PsbA1 (WT*1) or PsbA3 (WT*3) as the D1 protein was studied in whole cells of the thermophilic cyanobacterium Thermosynechococcus elongatus. When the cells are cultivated under high light conditions the following results were found: (i) The O₂ evolution activity decreases faster in WT*1 cells than in WT*3 cells both in the absence and in the presence of lincomycin, a protein synthesis inhibitor; (ii) In WT*1 cells, the rate constant for the decrease of the O₂ evolution activity is comparable in the presence and in the absence of lincomycin; (iii) The D1 content revealed by western blot analysis decays similarly in both WT*1 and WT*3 cells and much slowly than O₂ evolution; (iv) The faster decrease in O₂ evolution in WT*1 than in WT*3 cells correlates with a much faster inhibition of the S₂-state formation; (v) The shape of the WT*1 cells is altered. All these results are in agreement with a photo-inhibition process resulting in the loss of the O₂ activity much faster than the D1 turnover in PsbA1-PSII and likely to a greater production of reactive oxygen species under high light conditions in WT*1 than in WT*3. This latter result is discussed in view of the known effects of the PsbA1 to PsbA3 substitution on the redox properties of the Photosystem II cofactors. The observation that under low light conditions WT*3 cells are able to express the psbA₃ gene, whereas under similar conditions wild type cells are expressing mainly the psbA₁ gene is also discussed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.