Cl−‐dependent photovoltage responses of bacteriorhodopsin: comparison of the D85T and D85S mutants and wild‐type acid purple form

FEBS Letters

Kalaidzidis, Inna V¹  Kaulen, Andrey D¹ 

[1] Department of Photobiochemistry, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119899 Moscow, Russia

关键词: Bacteriorhodopsin;    Photocycle;    Photovoltage response;    Cl− transport;    D85S and D85T mutants;    Halobacterium salinarium;    bR;    bacteriorhodopsin;    hR;    halorhodopsin;    PM;    purple membrane;   

DOI  :  10.1016/S0014-5793(97)01390-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Laser flash-induced photovoltage responses of the D85S and D85T mutants as well as of the wild-type acid blue form are similar and reflect intraprotein charge redistribution caused by retinal isomerization. The Cl⁻-induced transition of all of these blue forms into purple ones is accompanied by the appearance of electrogenic stages, which is probably associated with Cl⁻ translocation in the cytoplasmic direction. Cl⁻ translocation efficiency of these purple forms is much lower than that of the proton transport by the wild-type bacteriorhodopsin. The values of the efficiency do not exceed 15, 8 and 3% for the D85T, D85S and wild-type acid purple form, respectively. Cl⁻ induces an additional electrogenic phase in the photovoltage responses of the D85S mutant and the wild-type acid purple form. This phase is supposed to be associated with the reversible Cl⁻ movement in the extracellular direction. It is interesting that this component is absent in the photovoltage response of the D85T mutant which has, like halorhodopsin, a threonine residue at position 85.

【 授权许可】

Unknown