Local Peptide Movement in the Photoreaction Intermediate of Rhodopsin

Photoactivation of the visual rhodopsin, a prototypical G proteincoupled receptor (GPCR), involves efficient conversion of the intrinsic inverse-agonist 11-cis-retinal to the all-trans agonist. This event leads to the rearrangement of the heptahelical transmembrane bundle, which is thought to be sha...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2006-08, Vol.103 (34), p.12729-12734
Main Authors: Nakamichi, Hitoshi, Okada, Tetsuji
Format: Article
Language:English
Subjects:
Agonists
Animals
Bathos
Biological Sciences
Cattle
Chromophores
Crystallography
Crystallography, X-Ray
Crystals
Datasets
Electron density
Ground state
Ligands
Membranes
Models, Molecular
Molecules
Peptides
Peptides - chemistry
Peptides - metabolism
Photochemistry
Pigments
Protein folding
Protein Structure, Tertiary
Receptors
Rhodopsin - chemistry
Rhodopsin - metabolism
Spectrum Analysis
Static Electricity
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Summary:Photoactivation of the visual rhodopsin, a prototypical G proteincoupled receptor (GPCR), involves efficient conversion of the intrinsic inverse-agonist 11-cis-retinal to the all-trans agonist. This event leads to the rearrangement of the heptahelical transmembrane bundle, which is thought to be shared by hundreds of GPCRs. To examine this activation mechanism, we determined the x-ray crystallographic model of the photoreaction intermediate of rhodopsin, lumirhodopsin, which represents the conformational state having the nearly complete all-trans agonist form of the retinal. A difference electron density map clearly indicated that the distorted all-trans-retinal in the precedent intermediate bathorhodopsin relaxes by dislocation of the β-ionone ring in lumirhodopsin, along with significant peptide displacement in the middle of helix III, including approximately two helical turns. This local movement results in the breaking of the electrostatic interhelical restraints mediated by many of the conserved residues among rhodopsin-like GPCRs, with consequent acquisition of full activity.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0601765103