Molecular basis for dramatic changes in cannabinoid CB1 G protein-coupled receptor activation upon single and double point mutations
Abstract
There is considerable interest in determining the activation mechanism of G protein-coupled receptors (GPCRs), one of the most important types of proteins for intercellular signaling. Recently, it was demonstrated for the cannabinoid CB1 GPCR, that a single mutation T210A could make CB1 completely inactive whereas T210I makes it essentially constitutively active. To obtain an understanding of this dramatic dependence of activity on mutation, we used first-principles-based methods to predict the ensemble of low-energy seven-helix conformations for the wild-type (WT) and mutants (T210A and T210I). We find that the transmembrane (TM) helix packings depend markedly on these mutations, leading for T210A to both TM3+TM6 and TM2+TM6 salt-bridge couplings in the cytoplasmic face that explains the inactivity of this mutant. In contrast T210I has no such couplings across the receptor explaining the ease in activating this mutant. WT has just the TM3+TM6 coupling, known to be broken upon GPCR activation. To test this hypothesis on activity, we predicted double mutants that would convert the inactive mutant to normal activity and then confirmed this experimentally. This CB1 activation mechanism, or one similar to it, is expected to play a role in other constitutively active GPCRs as well.
Additional Information
© 2012 The Protein Society. Received 5 September 2012; Accepted 26 October 2012. Published online 26 November 2012. The work in the laboratory of D.A.K. was supported by National Institutes of Health Grant DA020763. The work in the laboratory of W.A.G was initiated with gifts from PharmSelex/Accelerator and finished with funding from NIH grants (R01NS071112, R01NS073115, and R01AI040567) as well as from Sanofi.Attached Files
Supplemental Material - PRO_2192_sm_SuppInfo.doc
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Additional details
- PMCID
- PMC3575865
- Eprint ID
- 36463
- Resolver ID
- CaltechAUTHORS:20130118-083624400
- DA020763
- NIH
- R01NS071112
- NIH
- R01NS073115
- NIH
- R01AI040567
- NIH
- Sanofi
- Created
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2013-01-18Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field