NMR structure and action on nicotinic acetylcholine receptors of water-soluble domain of human LYNX1

J Biol Chem. 2011 Mar 25;286(12):10618-27. doi: 10.1074/jbc.M110.189100. Epub 2011 Jan 20.

Abstract

Discovery of proteins expressed in the central nervous system sharing the three-finger structure with snake α-neurotoxins provoked much interest to their role in brain functions. Prototoxin LYNX1, having homology both to Ly6 proteins and three-finger neurotoxins, is the first identified member of this family membrane-tethered by a GPI anchor, which considerably complicates in vitro studies. We report for the first time the NMR spatial structure for the water-soluble domain of human LYNX1 lacking a GPI anchor (ws-LYNX1) and its concentration-dependent activity on nicotinic acetylcholine receptors (nAChRs). At 5-30 μM, ws-LYNX1 competed with (125)I-α-bungarotoxin for binding to the acetylcholine-binding proteins (AChBPs) and to Torpedo nAChR. Exposure of Xenopus oocytes expressing α7 nAChRs to 1 μM ws-LYNX1 enhanced the response to acetylcholine, but no effect was detected on α4β2 and α3β2 nAChRs. Increasing ws-LYNX1 concentration to 10 μM caused a modest inhibition of these three nAChR subtypes. A common feature for ws-LYNX1 and LYNX1 is a decrease of nAChR sensitivity to high concentrations of acetylcholine. NMR and functional analysis both demonstrate that ws-LYNX1 is an appropriate model to shed light on the mechanism of LYNX1 action. Computer modeling, based on ws-LYNX1 NMR structure and AChBP x-ray structure, revealed a possible mode of ws-LYNX1 binding.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Animals
  • Bungarotoxins / chemistry
  • Bungarotoxins / pharmacology
  • GPI-Linked Proteins / chemistry*
  • GPI-Linked Proteins / genetics
  • GPI-Linked Proteins / metabolism
  • Humans
  • Models, Molecular*
  • Nuclear Magnetic Resonance, Biomolecular
  • Oocytes
  • Protein Binding
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Receptors, Nicotinic / chemistry*
  • Receptors, Nicotinic / genetics
  • Receptors, Nicotinic / metabolism
  • Solubility
  • Xenopus laevis

Substances

  • Adaptor Proteins, Signal Transducing
  • Bungarotoxins
  • GPI-Linked Proteins
  • LYNX1 protein, human
  • Receptors, Nicotinic

Associated data

  • PDB/2L03