3EAM

An open-pore structure of a bacterial pentameric ligand-gated ion channel

Summary for 3EAM

• Entry DOI: 10.2210/pdb3eam/pdb
• Descriptor: Glr4197 protein, DODECYL-BETA-D-MALTOSIDE, 1,2-DIACYL-SN-GLYCERO-3-PHOSPHOCHOLINE, ... (4 entities in total)
• Functional Keywords: pentameric ligand-gated ion-channel, membrane protein, transport protein
• Biological source: Gloeobacter violaceus
• Total number of polymer chains: 5
• Total formula weight: 196374.61

Authors

Bocquet, N.,Nury, H.,Baaden, M.,Le Poupon, C.,Changeux, J.P.,Delarue, M.,Corringer, P.J. (deposition date: 2008-08-26, release date: 2008-11-04, Last modification date: 2024-02-21)

Primary citation

Bocquet, N.,Nury, H.,Baaden, M.,Le Poupon, C.,Changeux, J.P.,Delarue, M.,Corringer, P.J.
X-ray structure of a pentameric ligand-gated ion channel in an apparently open conformation.
Nature, 457:111-114, 2009

PubMed Abstract: Pentameric ligand-gated ion channels from the Cys-loop family mediate fast chemo-electrical transduction, but the mechanisms of ion permeation and gating of these membrane proteins remain elusive. Here we present the X-ray structure at 2.9 A resolution of the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel homologue (GLIC) at pH 4.6 in an apparently open conformation. This cationic channel is known to be permanently activated by protons. The structure is arranged as a funnel-shaped transmembrane pore widely open on the outer side and lined by hydrophobic residues. On the inner side, a 5 A constriction matches with rings of hydrophilic residues that are likely to contribute to the ionic selectivity. Structural comparison with ELIC, a bacterial homologue from Erwinia chrysanthemi solved in a presumed closed conformation, shows a wider pore where the narrow hydrophobic constriction found in ELIC is removed. Comparative analysis of GLIC and ELIC reveals, in concert, a rotation of each extracellular beta-sandwich domain as a rigid body, interface rearrangements, and a reorganization of the transmembrane domain, involving a tilt of the M2 and M3 alpha-helices away from the pore axis. These data are consistent with a model of pore opening based on both quaternary twist and tertiary deformation.

PubMed: 18987633
DOI: 10.1038/nature07462

Experimental method

X-RAY DIFFRACTION (2.9 Å)