Structural basis for selectivity and diversity in angiotensin II receptors

Nature. 2017 Apr 20;544(7650):327-332. doi: 10.1038/nature22035. Epub 2017 Apr 5.

Abstract

The angiotensin II receptors AT1R and AT2R serve as key components of the renin-angiotensin-aldosterone system. AT1R has a central role in the regulation of blood pressure, but the function of AT2R is unclear and it has a variety of reported effects. To identify the mechanisms that underlie the differences in function and ligand selectivity between these receptors, here we report crystal structures of human AT2R bound to an AT2R-selective ligand and to an AT1R/AT2R dual ligand, capturing the receptor in an active-like conformation. Unexpectedly, helix VIII was found in a non-canonical position, stabilizing the active-like state, but at the same time preventing the recruitment of G proteins or β-arrestins, in agreement with the lack of signalling responses in standard cellular assays. Structure-activity relationship, docking and mutagenesis studies revealed the crucial interactions for ligand binding and selectivity. Our results thus provide insights into the structural basis of the distinct functions of the angiotensin receptors, and may guide the design of new selective ligands.

Publication types

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

MeSH terms

  • Angiotensin II Type 2 Receptor Blockers / chemistry
  • Angiotensin II Type 2 Receptor Blockers / metabolism
  • Binding Sites / genetics
  • Crystallography, X-Ray
  • Drug Design
  • Heterotrimeric GTP-Binding Proteins / chemistry
  • Heterotrimeric GTP-Binding Proteins / metabolism
  • Humans
  • Ligands
  • Models, Molecular*
  • Molecular Docking Simulation
  • Mutation
  • Protein Binding
  • Protein Conformation
  • Receptor, Angiotensin, Type 1 / chemistry
  • Receptor, Angiotensin, Type 1 / metabolism
  • Receptor, Angiotensin, Type 2 / agonists
  • Receptor, Angiotensin, Type 2 / chemistry*
  • Receptor, Angiotensin, Type 2 / genetics
  • Receptor, Angiotensin, Type 2 / metabolism*
  • Signal Transduction
  • Structure-Activity Relationship
  • Substrate Specificity / genetics
  • beta-Arrestins / metabolism

Substances

  • Angiotensin II Type 2 Receptor Blockers
  • Ligands
  • Receptor, Angiotensin, Type 1
  • Receptor, Angiotensin, Type 2
  • beta-Arrestins
  • Heterotrimeric GTP-Binding Proteins