Atomistic Insights into Rhodopsin Activation from a Dynamic Model

Irina G. Tikhonova, Robert B. Best, Stanislav Engel, Marvin C. Gershengorn, Gerhard Hummer, Stefano Costanzi

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Rhodopsin, the light sensitive receptor responsible for blue-green vision, serves as a prototypical G protein-coupled receptor (GPCR). Upon light absorption, it undergoes a series of conformational changes that lead to the active form, metarhodopsin II (META II), initiating a signaling cascade through binding to the G protein transducin (G(t)). Here, we first develop a structural model of META II by applying experimental distance restraints to the structure of lumi-rhodopsin (LUMI), an earlier intermediate. The restraints are imposed by using a combination of biased molecular dynamics simulations and perturbations to an elastic network model. We characterize the motions of the transmembrane helices in the LUMI-to-META II transition and the rearrangement of interhelical hydrogen bonds. We then simulate rhodopsin activation in a dynamic model to study the path leading from LUMI to our META II model for wild-type rhodopsin and a series of mutants. The simulations show a strong correlation between the transition dynamics and the pharmacological phenotypes of the mutants. These results help identify the molecular mechanisms of activation in both wild type and mutant rhodopsin. While static models can provide insights into the mechanisms of ligand recognition and predict ligand affinity, a dynamic model of activation could be applicable to study the pharmacology of other GPCRs and their ligands, offering a key to predictions of basal activity and ligand efficacy.

Original languageEnglish
Pages (from-to)10141-10149
Number of pages9
JournalJournal of the American Chemical Society
Issue number31
Early online date12 Jul 2008
Publication statusPublished - 06 Aug 2008

ASJC Scopus subject areas

  • Chemistry(all)

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    Tikhonova, I. G., Best, R. B., Engel, S., Gershengorn, M. C., Hummer, G., & Costanzi, S. (2008). Atomistic Insights into Rhodopsin Activation from a Dynamic Model. Journal of the American Chemical Society, 130(31), 10141-10149.