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

Nat Commun. 2018 Apr 10;9(1):1372. doi: 10.1038/s41467-018-03314-9.

Abstract

Cations play key roles in regulating G-protein-coupled receptors (GPCRs), although their mechanisms are poorly understood. Here, 19F NMR is used to delineate the effects of cations on functional states of the adenosine A2A GPCR. While Na+ reinforces an inactive ensemble and a partial-agonist stabilized state, Ca2+ and Mg2+ 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 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

Substances

  • Cations, Divalent
  • Receptor, Adenosine A2A
  • Recombinant Proteins
  • Triazines
  • Triazoles
  • ZM 241385
  • Adenosine-5'-(N-ethylcarboxamide)
  • Magnesium
  • Adenosine
  • Calcium