1IIT

GLUR0 LIGAND BINDING CORE COMPLEX WITH L-SERINE

1IIT の概要

• エントリーDOI: 10.2210/pdb1iit/pdb
• 関連するPDBエントリー: 1II5 1IIW
• 分子名称: Slr1257 protein, SERINE (3 entities in total)
• 機能のキーワード: membrane protein, same fold as pbps
• 由来する生物種: Synechocystis sp. PCC 6803 substr. Kazusa; 詳細
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 25671.07

構造登録者

Mayer, M.L.,Olson, R.,Gouaux, E. (登録日: 2001-04-24, 公開日: 2001-09-19, 最終更新日: 2024-02-07)

主引用文献

Mayer, M.L.,Olson, R.,Gouaux, E.
Mechanisms for ligand binding to GluR0 ion channels: crystal structures of the glutamate and serine complexes and a closed apo state.
J.Mol.Biol., 311:815-836, 2001

PubMed Abstract: High-resolution structures of the ligand binding core of GluR0, a glutamate receptor ion channel from Synechocystis PCC 6803, have been solved by X-ray diffraction. The GluR0 structures reveal homology with bacterial periplasmic binding proteins and the rat GluR2 AMPA subtype neurotransmitter receptor. The ligand binding site is formed by a cleft between two globular alpha/beta domains. L-Glutamate binds in an extended conformation, similar to that observed for glutamine binding protein (GlnBP). However, the L-glutamate gamma-carboxyl group interacts exclusively with Asn51 in domain 1, different from the interactions of ligand with domain 2 residues observed for GluR2 and GlnBP. To address how neutral amino acids activate GluR0 gating we solved the structure of the binding site complex with L-serine. This revealed solvent molecules acting as surrogate ligand atoms, such that the serine OH group makes solvent-mediated hydrogen bonds with Asn51. The structure of a ligand-free, closed-cleft conformation revealed an extensive hydrogen bond network mediated by solvent molecules. Equilibrium centrifugation analysis revealed dimerization of the GluR0 ligand binding core with a dissociation constant of 0.8 microM. In the crystal, a symmetrical dimer involving residues in domain 1 occurs along a crystallographic 2-fold axis and suggests that tetrameric glutamate receptor ion channels are assembled from dimers of dimers. We propose that ligand-induced conformational changes cause the ion channel to open as a result of an increase in domain 2 separation relative to the dimer interface.

PubMed: 11518533
DOI: 10.1006/jmbi.2001.4884

実験手法

X-RAY DIFFRACTION (1.9 Å)