Inhibition of the oxygen-evolving complex of photosystem II and depletion of extrinsic polypeptides by nickel |
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Authors: | Steve Boisvert David Joly Sébastien Leclerc Sridharan Govindachary Johanne Harnois Robert Carpentier |
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Affiliation: | (1) Groupe de recherche en Biologie Végétale, Université du Québec à Trois-Rivières, CP 500, Trois-Rivières, Québec, Canada, G9A 5H7 |
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Abstract: | The toxic effect of Ni2+ on photosynthetic electron transport was studied in a photosystem II submembrane fraction. It was shown that Ni2+ strongly inhibits oxygen evolution in the millimolar range of concentration. The inhibition was insensitive to NaCl but significantly decreased in the presence of CaCl2. Maximal chlorophyll fluorescence, together with variable fluorescence, maximal quantum yield of photosystem II, and flash-induced fluorescence decays were all significantly declined by Ni2+. Further, the extrinsic polypeptides of 16 and 24 kDa associated with the oxygen-evolving complex of photosystem II were depleted following Ni2+ treatment. It was deduced that interaction of Ni2+ with these polypeptides caused a conformational change that induced their release together with Ca2+ from the oxygen-evolving complex of photosystem II with consequent inhibition of the electron transport activity. |
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Keywords: | Electron transport Photosystem II Oxygen evolution Fluorescence Extrinsic polypeptides Heavy metals |
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