Structural impact of the E113Q counterion mutation on the activation and deactivation pathways of the G protein-coupled receptor rhodopsin.

ABSTRACT: Disruption of an interhelical salt bridge between the retinal protonated Schiff base linked to H7 and Glu113 on H3 is one of the decisive steps during activation of rhodopsin. Using previously established stabilization strategies, we engineered a stabilized E113Q counterion mutant that converted rhodopsin to a UV-absorbing photoreceptor with deprotonated Schiff base and allowed reconstitution into native-like lipid membranes. Fourier-transform infrared difference spectroscopy reveals a deprotonated Schiff base in the photoproducts of the mutant up to the active state Meta II, the absence of the classical pH-dependent Meta I/Meta II conformational equilibrium in favor of Meta II, and an anticipation of active state features under conditions that stabilize inactive photoproduct states in wil

SUBMITTER: Standfuss J 

PROVIDER: S-EPMC2726285 | biostudies-literature | 2008 Jun

REPOSITORIES: biostudies-literature