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How a small change in retinal leads to G‐protein activation: Initial events suggested by molecular dynamics calculations
Author(s) -
Crozier Paul S.,
Stevens Mark J.,
Woolf Thomas B.
Publication year - 2006
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.21175
Subject(s) - rhodopsin , conformational change , biophysics , retinal , chemistry , relaxation (psychology) , helix (gastropod) , protein structure , biology , biochemistry , neuroscience , ecology , snail
Rhodopsin is the prototypical G‐protein coupled receptor, coupling light activation with high efficiency to signaling molecules. The dark‐state X‐ray structures of the protein provide a starting point for consideration of the relaxation from initial light activation to conformational changes that may lead to signaling. In this study we create an energetically unstable retinal in the light activated state and then use molecular dynamics simulations to examine the types of compensation, relaxation, and conformational changes that occur following the cis–trans light activation. The results suggest that changes occur throughout the protein, with changes in the orientation of Helices 5 and 6, a closer interaction between Ala 169 on Helix 4 and retinal, and a shift in the Schiff base counterion that also reflects changes in sidechain interactions with the retinal. Taken together, the simulation is suggestive of the types of changes that lead from local conformational change to light‐activated signaling in this prototypical system. Proteins 2007. © 2006 Wiley‐Liss, Inc.