A local electrostatic change is the cause of the large-scale protein conformation shift in bacteriorhodopsin

Leonid S. Brown, Hironari Kamikubo, László Zimányi, Mikio Kataoka, Fumio Tokunaga, Peter Verdegem, Johan Lugtenburg, Janos K. Lanyi

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68 Citations (Scopus)

Abstract

During light-driven proton transport bacteriorhodopsin shuttles between two protein conformations. A large-scale structural change similar to that in the photochemical cycle is produced in the D85N mutant upon raising the pH, even without illumination. We report here that (i) the pK(a) values for the change in crystallographic parameters and for deprotonation of the retinal Schiff base are the same, (ii) the retinal isomeric configuration is nearly unaffected by the protein conformation, and (iii) preventing rotation of the C13-C14 double bond by replacing the retinal with an all-trans locked analogue makes little difference to the Schiff base pK(a). We conclude that the direct cause of the conformational shift is destabilization of the structure upon loss of interaction of the positively charged Schiff base with anionic residues that farm its counter-ion.

Original languageEnglish
Pages (from-to)5040-5044
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume94
Issue number10
DOIs
Publication statusPublished - May 13 1997

ASJC Scopus subject areas

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