His-75 in proteorhodopsin, a novel component in light-driven proton translocation by primary pumps.

ABSTRACT: Proteorhodopsins (PRs), photoactive retinylidene membrane proteins ubiquitous in marine eubacteria, exhibit light-driven proton transport activity similar to that of the well studied bacteriorhodopsin from halophilic archaea. However, unlike bacteriorhodopsin, PRs have a single highly conserved histidine located near the photoactive site of the protein. Time-resolved Fourier transform IR difference spectroscopy combined with visible absorption spectroscopy, isotope labeling, and electrical measurements of light-induced charge movements reveal participation of His-75 in the proton translocation mechanism of PR. Substitution of His-75 with Ala or Glu perturbed the structure of the photoactive site and resulted in significantly shifted visible absorption spectra. In contrast, His-75 substitut

SUBMITTER: Bergo VB 

PROVIDER: S-EPMC2631968 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature