Mechanistic insights into allosteric regulation of the A 2A adenosine G protein-coupled receptor by physiological cations

• Published in: Nature communications 2018-04, Vol.9 (1), p.1372
• Main Authors: Ye, Libin, Neale, Chris, Sljoka, Adnan, Lyda, Brent, Pichugin, Dmitry, Tsuchimura, Nobuyuki, Larda, Sacha T, Pomès, Régis, García, Angel E, Ernst, Oliver P, Sunahara, Roger K, Prosser, R Scott
• Format: Article
• Language: English
• Subjects: Adenosine - chemistry; Adenosine - metabolism; Adenosine-5'-(N-ethylcarboxamide) - chemistry; Adenosine-5'-(N-ethylcarboxamide) - metabolism; Allosteric Regulation; Amino Acid Sequence; Animals; Binding Sites; Calcium - chemistry; Calcium - metabolism; Cations, Divalent; Crystallography, X-Ray; Gene Expression; Humans; Kinetics; Magnesium - chemistry; Magnesium - metabolism; Models, Molecular; Molecular Dynamics Simulation; Protein Binding; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Receptor, Adenosine A2A - chemistry; Receptor, Adenosine A2A - genetics; Receptor, Adenosine A2A - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Sf9 Cells; Spodoptera; Thermodynamics; Triazines - chemistry; Triazines - metabolism; Triazoles - chemistry; Triazoles - metabolism
• ISSN: 2041-1723

Cations play key roles in regulating G-protein-coupled receptors (GPCRs), although their mechanisms are poorly understood. Here, F NMR is used to delineate the effects of cations on functional states of the adenosine A GPCR. While Na reinforces an inactive ensemble and a partial-agonist stabilized state, Ca and Mg shift the equilibrium toward active states. Positive allosteric effects of divalent cations are more pronounced with agonist and a G-protein-derived peptide. In cell membranes, divalent cations enhance both the affinity and fraction of the high affinity agonist-bound state. Molecular dynamics simulations suggest high concentrations of divalent cations bridge specific extracellular acidic residues, bringing TM5 and TM6 together at the extracellular surface and allosterically driving open the G-protein-binding cleft as shown by rigidity-transmission allostery theory. An understanding of cation allostery should enable the design of allosteric agents and enhance our understanding of GPCR regulation in the cellular milieu.