2XZ5

MMTS-modified Y53C mutant of Aplysia AChBP in complex with acetylcholine


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.219 
  • R-Value Work: 0.173 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal Structures of a Cysteine-Modified Mutant in Loop D of Acetylcholine Binding Protein

Brams, M.Gay, E.A.Colon Saez, J.Guskov, A.Van Elk, R.Van Der Schors, R.C.Peigneur, S.Tytgat, J.Strelkov, S.V.Smit, A.B.Yakel, J.L.Ulens, C.

(2011) J.Biol.Chem. 286: 4420

  • DOI: 10.1074/jbc.M110.188730
  • Primary Citation of Related Structures:  2XZ6

  • PubMed Abstract: 
  • Covalent modification of α7 W55C nicotinic acetylcholine receptors (nAChR) with the cysteine-modifying reagent [2-(trimethylammonium)ethyl] methanethiosulfonate (MTSET(+)) produces receptors that are unresponsive to acetylcholine, whereas methyl meth ...

    Covalent modification of α7 W55C nicotinic acetylcholine receptors (nAChR) with the cysteine-modifying reagent [2-(trimethylammonium)ethyl] methanethiosulfonate (MTSET(+)) produces receptors that are unresponsive to acetylcholine, whereas methyl methanethiolsulfonate (MMTS) produces enhanced acetylcholine-gated currents. Here, we investigate structural changes that underlie the opposite effects of MTSET(+) and MMTS using acetylcholine-binding protein (AChBP), a homolog of the extracellular domain of the nAChR. Crystal structures of Y53C AChBP show that MTSET(+)-modification stabilizes loop C in an extended conformation that resembles the antagonist-bound state, which parallels our observation that MTSET(+) produces unresponsive W55C nAChRs. The MMTS-modified mutant in complex with acetylcholine is characterized by a contracted C-loop, similar to other agonist-bound complexes. Surprisingly, we find two acetylcholine molecules bound in the ligand-binding site, which might explain the potentiating effect of MMTS modification in W55C nAChRs. Unexpectedly, we observed in the MMTS-Y53C structure that ten phosphate ions arranged in two rings at adjacent sites are bound in the vestibule of AChBP. We mutated homologous residues in the vestibule of α1 GlyR and observed a reduction in the single channel conductance, suggesting a role of this site in ion permeation. Taken together, our results demonstrate that targeted modification of a conserved aromatic residue in loop D is sufficient for a conformational switch of AChBP and that a defined region in the vestibule of the extracellular domain contributes to ion conduction in anion-selective Cys-loop receptors.


    Organizational Affiliation

    Laboratory of Structural Neurobiology, KULeuven, 3000 Leuven, Belgium.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
SOLUBLE ACETYLCHOLINE RECEPTOR
A, B, C, D, E
217Aplysia californicaN/A
Find proteins for Q8WSF8 (Aplysia californica)
Go to UniProtKB:  Q8WSF8
Small Molecules
Ligands 5 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACH
Query on ACH

Download SDF File 
Download CCD File 
A, B, C, D, E
ACETYLCHOLINE
C7 H16 N O2
OIPILFWXSMYKGL-UHFFFAOYSA-N
 Ligand Interaction
PO4
Query on PO4

Download SDF File 
Download CCD File 
A, B, C, D, E
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
CL
Query on CL

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Download CCD File 
A, B, C, D, E
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
NAG
Query on NAG

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Download CCD File 
D
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
MPD
Query on MPD

Download SDF File 
Download CCD File 
A, B, C, D, E
(4S)-2-METHYL-2,4-PENTANEDIOL
C6 H14 O2
SVTBMSDMJJWYQN-YFKPBYRVSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
SCH
Query on SCH
A, B, C, D, E
L-PEPTIDE LINKINGC4 H9 N O2 S2CYS
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
ACHKi: 98300 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.219 
  • R-Value Work: 0.173 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 82.123α = 90.00
b = 119.405β = 90.00
c = 267.744γ = 90.00
Software Package:
Software NamePurpose
BUSTERrefinement
MOLREPphasing
XDSdata reduction
XSCALEdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-12-08
    Type: Initial release
  • Version 1.1: 2011-08-10
    Type: Atomic model, Other, Version format compliance
  • Version 1.2: 2014-02-05
    Type: Refinement description