Structure and selectivity engineering of the M1 muscarinic receptor toxin complex

Science. 2020 Jul 10;369(6500):161-167. doi: 10.1126/science.aax2517.

Abstract

Muscarinic toxins (MTs) are natural toxins produced by mamba snakes that primarily bind to muscarinic acetylcholine receptors (MAChRs) and modulate their function. Despite their similar primary and tertiary structures, MTs show distinct binding selectivity toward different MAChRs. The molecular details of how MTs distinguish MAChRs are not well understood. Here, we present the crystal structure of M1AChR in complex with MT7, a subtype-selective anti-M1AChR snake venom toxin. The structure reveals the molecular basis of the extreme subtype specificity of MT7 for M1AChR and the mechanism by which it regulates receptor function. Through in vitro engineering of MT7 finger regions that was guided by the structure, we have converted the selectivity from M1AChR toward M2AChR, suggesting that the three-finger fold is a promising scaffold for developing G protein-coupled receptor modulators.

Publication types

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

MeSH terms

  • Animals
  • Atropine / chemistry
  • Crystallography, X-Ray
  • Elapid Venoms / chemistry*
  • Genetic Engineering
  • Muscarinic Antagonists / chemistry
  • Protein Conformation
  • Receptor, Muscarinic M1 / antagonists & inhibitors
  • Receptor, Muscarinic M1 / chemistry*
  • Receptor, Muscarinic M1 / genetics*
  • Sf9 Cells

Substances

  • Elapid Venoms
  • Muscarinic Antagonists
  • Receptor, Muscarinic M1
  • m1-toxin
  • Atropine