4ILB

The pentameric ligand-gated ion channel GLIC A237F in complex with Rubidium

Summary for 4ILB

• Entry DOI: 10.2210/pdb4ilb/pdb
• Related: 4HFI 4IL4 4IL9 4ILA 4ILC
• Descriptor: Proton-gated ion channel, DODECYL-BETA-D-MALTOSIDE, DIUNDECYL PHOSPHATIDYL CHOLINE, ... (9 entities in total)
• Functional Keywords: pentameric ligand-gated ion channel, ion channel, membrane, membrane protein, transport protein
• Biological source: Gloeobacter violaceus
• Cellular location: Cell inner membrane; Multi-pass membrane protein (Probable): Q7NDN8
• Total number of polymer chains: 5
• Total formula weight: 192817.95

Authors

Sauguet, L.,Corringer, P.J.,Delarue, M. (deposition date: 2012-12-29, release date: 2013-02-20, Last modification date: 2023-09-20)

Primary citation

Sauguet, L.,Poitevin, F.,Murail, S.,Van Renterghem, C.,Moraga-Cid, G.,Malherbe, L.,Thompson, A.W.,Koehl, P.,Corringer, P.J.,Baaden, M.,Delarue, M.
Structural basis for ion permeation mechanism in pentameric ligand-gated ion channels.
Embo J., 32:728-741, 2013

PubMed Abstract: To understand the molecular mechanism of ion permeation in pentameric ligand-gated ion channels (pLGIC), we solved the structure of an open form of GLIC, a prokaryotic pLGIC, at 2.4 Å. Anomalous diffraction data were used to place bound anions and cations. This reveals ordered water molecules at the level of two rings of hydroxylated residues (named Ser6' and Thr2') that contribute to the ion selectivity filter. Two water pentagons are observed, a self-stabilized ice-like water pentagon and a second wider water pentagon, with one sodium ion between them. Single-channel electrophysiology shows that the side-chain hydroxyl of Ser6' is crucial for ion translocation. Simulations and electrostatics calculations complemented the description of hydration in the pore and suggest that the water pentagons observed in the crystal are important for the ion to cross hydrophobic constriction barriers. Simulations that pull a cation through the pore reveal that residue Ser6' actively contributes to ion translocation by reorienting its side chain when the ion is going through the pore. Generalization of these findings to the pLGIC family is proposed.

PubMed: 23403925
DOI: 10.1038/emboj.2013.17

Experimental method

X-RAY DIFFRACTION (3.15 Å)