1IIW
GLUR0 LIGAND BINDING CORE: CLOSED-CLEFT LIGAND-FREE STRUCTURE
Summary for 1IIW
| Entry DOI | 10.2210/pdb1iiw/pdb |
| Related | 1II5 1IIT |
| Descriptor | Slr1257 protein (2 entities in total) |
| Functional Keywords | fold related to pbps, membrane protein |
| Biological source | Synechocystis sp. PCC 6803 substr. Kazusa More |
| Total number of polymer chains | 1 |
| Total formula weight | 25565.98 |
| Authors | Mayer, M.L.,Olson, R.,Gouaux, E. (deposition date: 2001-04-24, release date: 2001-09-19, Last modification date: 2024-02-07) |
| Primary citation | 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 Cited by 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: 11518533DOI: 10.1006/jmbi.2001.4884 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.9 Å) |
Structure validation
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