Thr90 is a key residue of the bacteriorhodopsin proton pumping mechanism

FEBS Letters

Sabés, Manuel¹  Perálvarez, Alex¹  Padrós, Esteve¹  Barnadas, Ramon¹  Querol, Enric² 

[1] Unitat de Biofı́sica, Departament de Bioquı́mica i de Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Barcelona 08193, Spain;Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), Barcelona 08193, Spain

关键词: Bacteriorhodopsin;    Proton pumping;    Helical kink;    Conformational change;    Hydrogen bonding;    Thermal stability;    BR;    bacteriorhodopsin;    DSC;    differential scanning calorimetry;    EPC;    egg yolk phosphatidylcholine;   

DOI  :  10.1016/S0014-5793(01)03080-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Mutation of Thr90 to Ala has a profound effect on bacteriorhodopsin properties. T90A shows about 20% of the proton pumping efficiency of wild type, once reconstituted into liposomes. Mutation of Thr90 influences greatly the Schiff base/Asp85 environment, as demonstrated by altered λ _max of 555 nm and pK _a of Asp85 (about 1.3 pH units higher than wild type). Hydroxylamine accessibility is increased in both dark and light and differential scanning calorimetry and visible spectrophotometry show decreased thermal stability. These results suggest that Thr90 has an important structural role in both the unphotolysed bacteriorhodopsin and in the proton pumping mechanism.

【 授权许可】

Unknown