Allosteric regulation of G protein–coupled receptor activity by phospholipids

Abstract

Lipids are emerging as key regulators of membrane protein structure and activity. Such effects can either be attributed to modification in bilayer properties (thickness, curvature and surface tension) or to binding of specific lipids to the protein surface. For G Protein-Coupled Receptors (GPCRs), the effect of phospholipids on receptor structure and activity remains poorly understood. Here we reconstituted purified β2-adrenergic receptor in High-Density-Lipoparticles to systematically characterize the effect of biologically relevant phospholipids on receptor activity. We observe that the lipid head-group type affects ligand binding (agonist and antagonist) and receptor activation. Specifically, phosphatidylgycerol markedly favors agonist binding and facilitates receptor activation while phosphatidylethanolamine favors antagonist binding and stabilizes the inactive state of the receptor. We then show that these effects can be recapitulated with detergent-solubilized lipids, demonstrating that the functional modulation occurs in the absence of a bilayer. Our data suggest that phospholipids act as direct allosteric modulators of GPCR activity.

Lipid-Mediated Regulation of Embedded Receptor Kinases via Parallel Allosteric Relays

“…The lipid composition of the membrane is a key determinant of the allosteric modulation of receptor function for some receptors (37,39,53). However, in the case of EnvZ, we observed no significant differences in enzymatic activity between the physiological E. coli lipids and the nonbacterial phospholipid DOPC.…”

“…Similar allosteric modulation of receptor function has been demonstrated in diverse membrane protein families, including G-protein-coupled receptors, receptor tyrosine kinases, and proton channels (37,39,(41)(42)(43)(44), as well as soluble cytoplasmic proteins containing lipid-targeting domains (45,46). Lipids impact the structure and function of membrane-embedded or membrane-associated proteins either through bulk effects mediated by the phospholipid bilayer or through binding of lipid molecules at specific sites (40,(47)(48)(49)(50).…”

“…Lipids are thus increasingly being recognized for mediating divergent regulatory roles in controlling associated embedded membrane protein function (37)(38)(39)(40). In this study, we demonstrate how lipid-mediated allostery has a profound impact on receptor function, which has direct implications for understanding TM receptor signaling mechanisms.…”

G protein-coupled receptor-receptor interactions give integrative dynamics to intercellular communication

“…Recently, relevant phospholipids were found to affect GPCR function. In β 2 -adrenergic receptors reconstituted in high-density lipoparticles, for instance, phosphatidylgycerol markedly favored agonist binding and facilitated receptor activation, whereas phosphatidylethanolamine favored antagonist binding and stabilized the inactive state of the receptor ( Dawaliby et al, 2016). These data suggested that phospholipids could act as direct allosteric modulators of GPCR activity.…”

Probing Conformational Changes during the Gating Cycle of a Potassium Channel in Lipid Bilayers

“…These contacts play important roles in membrane protein folding, structure, and function (1). Binding of lipids to specific sites has been observed in crystal structures (2), and increasing evidence suggests that membrane lipids play a critical functional role in a variety of membrane protein classes, including channels (3)(4)(5)(6), transporters (7), G-protein coupled receptors (8), and receptor tyrosine kinases (9).…”