3EI0

Structure of the E221A mutant of the Gloebacter violaceus pentameric ligand gated ion channnel (GLIC)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.5 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.255 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structure of a potentially open state of a proton-activated pentameric ligand-gated ion channel

Hilf, R.J.Dutzler, R.

(2008) Nature 457: 115-118

  • DOI: 10.1038/nature07461
  • Primary Citation of Related Structures:  
  • Also Cited By: 2XQA, 2XQ9, 2XQ8, 2XQ7, 2XQ6, 2XQ5, 2XQ4, 2XQ3

  • PubMed Abstract: 
  • The X-ray structure of a pentameric ligand-gated ion channel from Erwinia chrysanthemi (ELIC) has recently provided structural insight into this family of ion channels at high resolution. The structure shows a homo-pentameric protein with a barrel-st ...

    The X-ray structure of a pentameric ligand-gated ion channel from Erwinia chrysanthemi (ELIC) has recently provided structural insight into this family of ion channels at high resolution. The structure shows a homo-pentameric protein with a barrel-stave architecture that defines an ion-conduction pore located on the fivefold axis of symmetry. In this structure, the wide aqueous vestibule that is encircled by the extracellular ligand-binding domains of the five subunits narrows to a discontinuous pore that spans the lipid bilayer. The pore is constricted by bulky hydrophobic residues towards the extracellular side, which probably serve as barriers that prevent the diffusion of ions. This interrupted pore architecture in ELIC thus depicts a non-conducting conformation of a pentameric ligand-gated ion channel, the thermodynamically stable state in the absence of bound ligand. As ligand binding promotes pore opening in these ion channels and the specific ligand for ELIC has not yet been identified, we have turned our attention towards a homologous protein from the cyanobacterium Gloebacter violaceus (GLIC). GLIC was shown to form proton-gated channels that are activated by a pH decrease on the extracellular side and that do not desensitize after activation. Both prokaryotic proteins, ELIC and GLIC form ion channels that are selective for cations over anions with poor discrimination among monovalent cations, characteristics that resemble the conduction properties of the cation-selective branch of the family that includes acetylcholine and serotonin receptors. Here we present the X-ray structure of GLIC at 3.1 A resolution. The structure reveals a conformation of the channel that is distinct from ELIC and that probably resembles the open state. In combination, both structures suggest a novel gating mechanism for pentameric ligand-gated ion channels where channel opening proceeds by a change in the tilt of the pore-forming helices.


    Organizational Affiliation

    Department of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Glr4197 protein
A, B, C, D, E
317Gloeobacter violaceus (strain PCC 7421)Mutation(s): 1 
Gene Names: glvI
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Cys-Loop Receptor Family
Protein: 
Prokaryotic pentameric ligand-gated ion channel (GLIC)
Find proteins for Q7NDN8 (Gloeobacter violaceus (strain PCC 7421))
Go to UniProtKB:  Q7NDN8
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.5 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.255 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 179.638α = 90.00
b = 133.765β = 101.67
c = 161.647γ = 90.00
Software Package:
Software NamePurpose
SCALAdata scaling
PHASERphasing
MOSFLMdata reduction
PHENIXrefinement
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-11-11
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance