A Molecular Mechanism for Sequential Activation of a G Protein-Coupled Receptor. Issue 3 (17th March 2016)

• Record Type: Journal Article
• Authors: Grundmann, Manuel; Tikhonova, Irina G.; Hudson, Brian D.; Smith, Nicola J.; Mohr, Klaus; Ulven, Trond; Milligan, Graeme; Kenakin, Terry; Kostenis, Evi
• Is Part Of: Cell chemical biology. Volume 23:Issue 3(2016)
• Page Start: 392
• Page End: 403
• Publication Date: 2016-03-17
• Subjects: Biochemistry -- Periodicals; 572.05
• DOI: 10.1016/j.chembiol.2016.02.014
• Languages: English
• ISSNs: 2451-9456

Abstract

Summary: Ligands targeting G protein-coupled receptors (GPCRs) are currently classified as either orthosteric, allosteric, or dualsteric/bitopic. Here, we introduce a new pharmacological concept for GPCR functional modulation: sequential receptor activation . A hallmark feature of this is a stepwise ligand binding mode with transient activation of a first receptor site followed by sustained activation of a second topographically distinct site. We identify 4-CMTB (2-(4-chlorophenyl)-3-methyl-N-(thiazol-2-yl)butanamide), previously classified as a pure allosteric agonist of the free fatty acid receptor 2, as the first sequential activator and corroborate its two-step activation in living cells by tracking integrated responses with innovative label-free biosensors that visualize multiple signaling inputs in real time. We validate this unique pharmacology with traditional cellular readouts, including mutational and pharmacological perturbations along with computational methods, and propose a kinetic model applicable to the analysis of sequential receptor activation. We envision this form of dynamic agonism as a common principle of nature to spatiotemporally encode cellular information. Graphical Abstract: Highlights: Label-free biosensors disclose novel mechanism of receptor activation Allosteric agonist 4-CMTB sequentially activates free fatty acid receptor 2 (FFA2) 4-CMTB engages two topographically distinct FFA2 sites in a stepwise mechanism Sequential receptor activation as another means to encode cell signaling dynamics Abstract : Current activation modes of G protein-coupled receptors include orthosteric, allosteric, or dualsteric/bitopic concepts. By redefining the mode of action of a small molecule, previously thought of as purely allosteric, Grundmann et al. introduce yet another principle of nature to spatiotemporally encode cellular information using a two-step process: sequential receptor activation .