Download MendeleyAllosteric modulation and biased signalling at free fatty acid receptor 2.
Zhang, X., Guseinov, A.A., Jenkins, L., Valentini, A., Marsango, S., Schultz-Knudsen, K., Ulven, T., Rexen Ulven, E., Tikhonova, I.G., Milligan, G., Zhang, C.(2025) Nature 643: 1428-1438
- PubMed: 40533560
- DOI: https://doi.org/10.1038/s41586-025-09186-6
- Primary Citation of Related Structures:
9CLW, 9CM3, 9CM7, 9NS9 - PubMed Abstract:
Free fatty acid receptor 2 (FFA2) is a G protein-coupled receptor (GPCR) that is a primary sensor for short-chain fatty acids produced by gut microbiota. Consequently, FFA2 is a promising drug target for immunometabolic disorders 1-4 . Here we report cryogenic electronic microscopy structures of FFA2 in complex with two G proteins and three distinct classes of positive allosteric modulators (PAMs), and describe noncanonical activation mechanisms that involve conserved structural features of class A GPCRs. Two PAMs disrupt the E/DRY activation microswitch 5 and stabilize the conformation of intracellular loop 2 by binding to lipid-facing pockets near the cytoplasmic side of the receptor. By contrast, the third PAM promotes the separation of transmembrane helices 6 and 7 by interacting with transmembrane helix 6 at the receptor-lipid interface. Molecular dynamic simulations and mutagenesis experiments confirm these noncanonical activation mechanisms. Furthermore, we demonstrate the molecular basis for the G i versus G q bias, which is due to distinct conformations of intracellular loop 2 stabilized by different PAMs. These findings provide a framework for the design of tailored GPCR modulators, with implications that extend beyond FFA2 to the broader field of GPCR drug discovery.
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
Organizational Affiliation:
