Hotspots of Efficacy in GPCRs

Published 28 January 2021 in eLife (doi 10.7554/eLife.60715):

Identification of ligand-specific G-protein coupled receptor states and prediction of downstream efficacy via data-driven modeling

Oliver Fleetwood, Jens Carlsson, Lucie Delemotte

Ligand binding stabilizes different G protein-coupled receptor states via a complex allosteric process that is not completely understood. Here, we have derived free energy landscapes describing activation of the β2 adrenergic receptor bound to ligands with different efficacy profiles using enhanced sampling molecular dynamics (MD) simulations. These reveal shifts towards active-like states at the G protein binding site for receptors bound to partial and full agonists and that the ligands modulate the conformational ensemble of the receptor by tuning protein microswitches. We indeed find an excellent correlation between the conformation of the microswitches close to the ligand binding site and in the transmembrane region and experimentally reported cAMP signaling responses. Dimensionality reduction further reveals the similarity between the unique conformational states induced by different ligands and examining the output of classifiers highlights two distant hotspots governing agonism on transmembrane helices 5 and 7.

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