3EI0

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

3EI0 の概要

• エントリーDOI: 10.2210/pdb3ei0/pdb
• 関連するPDBエントリー: 3EHZ
• 分子名称: Glr4197 protein (1 entity in total)
• 機能のキーワード: pentameric ligand gated ion channel, membrane protein, prokaryotic cys-loop receptor, cation selective channel
• 由来する生物種: Gloeobacter violaceus
• タンパク質・核酸の鎖数: 5
• 化学式量合計: 181098.44

構造登録者

Hilf, R.J.C.,Dutzler, R. (登録日: 2008-09-15, 公開日: 2008-11-11, 最終更新日: 2023-11-01)

主引用文献

Hilf, R.J.,Dutzler, R.
Structure of a potentially open state of a proton-activated pentameric ligand-gated ion channel
Nature, 457:115-118, 2008

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. 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.

PubMed: 18987630
DOI: 10.1038/nature07461

実験手法

X-RAY DIFFRACTION (3.5 Å)