3EI0

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


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.50 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.255 
  • R-Value Observed: 0.256 

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This is version 1.2 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:  
    3EHZ, 3EI0

  • 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-stave architecture that defines an ion-conduction pore located on the fivefold axis of symmetry ...

    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:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Glr4197 proteinA, B, C, D, E317Gloeobacter violaceusMutation(s): 1 
Membrane Entity: Yes 
UniProt
Find proteins for Q7NDN8 (Gloeobacter violaceus (strain ATCC 29082 / PCC 7421))
Explore Q7NDN8 
Go to UniProtKB:  Q7NDN8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ7NDN8
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.50 Å
  • R-Value Free: 0.276 
  • R-Value Work: 0.255 
  • R-Value Observed: 0.256 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 179.638α = 90
b = 133.765β = 101.67
c = 161.647γ = 90
Software Package:
Software NamePurpose
SCALAdata scaling
PHASERphasing
PHENIXrefinement
PDB_EXTRACTdata extraction
MOSFLMdata reduction

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-11-11
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-11-10
    Changes: Database references