Allosteric Coupling of Drug Binding and Intracellular Signaling in the A_2A Adenosine Receptor.

Abstract

Signaling across cellular membranes, the 826 human G protein-coupled receptors (GPCRs) govern a wide range of vital physiological processes, making GPCRs prominent drug targets. X-ray crystallography provided GPCR molecular architectures, which also revealed the need for additional structural dynamics data to support drug development. Here, nuclear magnetic resonance (NMR) spectroscopy with the wild-type-like A_2A adenosine receptor (A_2AAR) in solution provides a comprehensive characterization of signaling-related structural dynamics. All six tryptophan indole and eight glycine backbone ¹⁵N-¹H NMR signals in A_2AAR were individually assigned. These NMR probes provided insight into the role of Asp52^2.50 as an allosteric link between the orthosteric drug binding site and the intracellular signaling surface, revealing strong interactions with the toggle switch Trp 246^6.48, and delineated the structural response to variable efficacy of bound drugs across A_2AAR. The present data support GPCR signaling based on dynamic interactions between two semi-independent subdomains connected by an allosteric switch at Asp52^2.50.