Molecular mechanism of action of Pb2+ and Zn2+ on water oxidizing complex of photosystem II

FEBS Letters

Camm, Edith L.¹  Ekramoddoullah, Abul K.M.²  Rashid, Abdur¹ 

[1] Department of Botany, University of British Columbia, Vancouver, B.C. V6T 1Z4, Canada;Natural Resources Canada, Pacific Forestry Centre, Victoria, B.C. V8Z 1M5, Canada

关键词: Photosystem II;    Oxygen evolving complex;    Extrinsic polypeptides;    Immunoblotting;    Lead action;    Zinc action;    PSII;    photosystem II;    OEC;    oxygen evolving complex;    SDS-PAGE;    sodium dodecylsulfate-polyacrylamide gel electrophoresis;   

DOI  :  10.1016/0014-5793(94)00789-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Pb²⁺ and Zn²⁺ inhibition of photosystem II (PSII) activity was reported to be mediated via displacement of native inorganic cofactors (Cl⁻, Ca²⁺ and Mn²⁺) from the oxygen evolving complex, OEC [Rashid and Popovic (1990) FEBS Lett. 271, 181–184; Rashid et al. (1991) Photosynth. Res. 30, 123–130]. Since the binding sites of these cofactors are protected by a shield of three extrinsic polypeptides (17, 23 and 33 kDa), we investigated whether these metal ions affect the extrinsic polypeptide shield of OEC. By immunoblotting with antibodies recognizing the 23 and 33 kDa polypeptides, we showed that both the metal ions significantly dissociated the 23 kDa (+17 kDa) polypeptide, and partially dissociated the 33 kDa. Ca²⁺, one of the important inorganic cofactors of oxygen evolution, strongly prevented the dissociating action of Pb²⁺ but did not prevent the action of Zn²⁺. The probable molecular mechanism of action of Pb²⁺ and Zn²⁺ on PSII OEC is discussed.

【 授权许可】

Unknown