Mercury inhibition at the donor side of photosystem II is reversed by chloride

FEBS Letters

Carpentier, Robert¹  Bernier, Michelle¹  Popovic, Radovan² 

[1] Centre de recherche en photobiophysique, Université du Québec à Trois-Rivières, C.P. 500, Trois-Riviéres, Québec, G9Z 5H7, Canada;Département de chimie, Université du Québec á Montréal, C.P. 8888, Montréal, Québec, H3C 3P8, Canada

关键词: Photosystem II;    Electron transport;    Oxygen evolution;    Mercury;    Chloride;    Calcium;    Chl;    chlorophyll;    DCBQ;    2;    5-dichlorobenzoquinone;    EP;    extrinsic protein;    F o;    constant fluorescence;    F v;    max;    maximum value for variable fluorescence;    K n;    stability constant of metallic complexes;    MES;    2-(N-morpholino)ethanesulfonic acid;    PSII;    photosystem II;    TMA;    tetramethyl ammonium;   

DOI  :  10.1016/0014-5793(93)80612-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Mercury is an environmental contaminant that strongly inhibits photosynthetic electron transport, photosystem II being the most sensitive target. We investigated in greater detail the effect of mercury using photosystem II submembrane fractions of higher plants. Oxygen evolution was strongly inhibited and variable chlorophyll fluorescence was severely quenched by mercury. Chloride, an inorganic cofactor known to be essential for the optimal function of photosystem II, significantly reversed the inhibitory effect of mercury. However, calcium, another essential cofactor, showed no reversal capacity. It is concluded that on the donor side of PSII, mercury exerts its action by perturbing chloride binding and/or function. Considering the exceptional affinity of mercury for sulfhydryl groups of proteins, the results suggest the implication of cystein residue(s) in maintaining structural and functional integrity of photosystem II.

【 授权许可】

Unknown