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| - | [[Image:1iit.gif|left|200px]] | + | {{Seed}} |
| | + | [[Image:1iit.png|left|200px]] |
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| | {{STRUCTURE_1iit| PDB=1iit | SCENE= }} | | {{STRUCTURE_1iit| PDB=1iit | SCENE= }} |
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| - | '''GLUR0 LIGAND BINDING CORE COMPLEX WITH L-SERINE'''
| + | ===GLUR0 LIGAND BINDING CORE COMPLEX WITH L-SERINE=== |
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| - | ==Overview==
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| - | 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.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_11518533}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 11518533 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_11518533}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Membrane protein]] | | [[Category: Membrane protein]] |
| | [[Category: Same fold as pbp]] | | [[Category: Same fold as pbp]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 20:03:04 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 12:17:30 2008'' |
Revision as of 09:17, 1 July 2008
Template:STRUCTURE 1iit
GLUR0 LIGAND BINDING CORE COMPLEX WITH L-SERINE
Template:ABSTRACT PUBMED 11518533
About this Structure
1IIT is a Single protein structure of sequence from Synechocystis sp.. Full crystallographic information is available from OCA.
Reference
Mechanisms for ligand binding to GluR0 ion channels: crystal structures of the glutamate and serine complexes and a closed apo state., Mayer ML, Olson R, Gouaux E, J Mol Biol. 2001 Aug 24;311(4):815-36. PMID:11518533
Page seeded by OCA on Tue Jul 1 12:17:30 2008
