Inhibition of the oxygen-evolving complex of photosystem II and depletion of extrinsic polypeptides by nickel.
The toxic effect of Ni(2+) on photosynthetic electron transport was studied in a photosystem II submembrane fraction. It was shown that Ni(2+) strongly inhibits oxygen evolution in the millimolar range of concentration. The inhibition was insensitive to NaCl but significantly decreased in the presence of CaCl(2). Maximal chlorophyll fluorescence, together with variable fluorescence, maximal quantum yield of photosystem II, and flash-induced fluorescence decays were all significantly declined by Ni(2+). Further, the extrinsic polypeptides of 16 and 24 kDa associated with the oxygen-evolving complex of photosystem II were depleted following Ni(2+) treatment. It was deduced that interaction of Ni(2+) with these polypeptides caused a conformational change that induced their release together with Ca(2+) from the oxygen-evolving complex of photosystem II with consequent inhibition of the electron transport activity.
Boisvert
Steve
S
Groupe de recherche en Biologie Végétale, Université du Québec à Trois-Rivières, CP 500, Trois-Rivières, Québec, Canada G9A 5H7.
Joly
David
D
Leclerc
Sébastien
S
Govindachary
Sridharan
S
Harnois
Johanne
J
Carpentier
Robert
R
D002122:Calcium Chloride / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport; D004583:Electrons; D007700:Kinetics; D008345:Manganese / Q000737:chemistry; D008670:Metals / Q000737:chemistry; D008856:Microscopy, Fluorescence; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry*; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D013997:Time Factors
D008670:Metals; D010455:Peptides; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D008345:Manganese; C022838:nickel chloride; D009532:Nickel; D002122:Calcium Chloride; D010100:Oxygen