2ZNS: Crystal Structure Of The Ligand-binding Core Of The Human Ionotropic Glutamate Receptor, Glur5, In Complex With Glutamate

Citation:
Abstract
Dysiherbaine (DH) and neodysiherbaine A (NDH) selectively bind and activate two kainate-type ionotropic glutamate receptors, GluK1 and GluK2. The ligand-binding domains of human GluK1 and GluK2 were crystallized as bound forms with a series of DH analogues including DH, NDH, 8-deoxy-NDH, 9-deoxy-NDH and 8,9-dideoxy-NDH (MSVIII-19), isolated from natural sources or prepared by total synthesis. Since the DH analogues exhibit a wide range of binding affinities and agonist efficacies, it follows that the detailed analysis of crystal structure would provide us with a significant opportunity to elucidate structural factors responsible for selective binding and some aspects of gating efficacy. We found that differences in three amino acids (Thr503, Ser706 and Ser726 in GluK1 and Ala487, Asn690 and Thr710 in GluK2) in the ligand-binding pocket generate differences in the binding modes of NDH to GluK1 and GluK2. Furthermore, deletion of the C(9) hydroxy group in NDH alters the ligand conformation such that it is no longer suited for binding to the GluK1 ligand-binding pocket. In GluK2, NDH pushes and rotates the side chain of Asn690 (substituted for Ser706 in GluK1) and disrupts an interdomain hydrogen bond with Glu409. The present data support the idea that receptor selectivities of DH analogues resulted from the differences in the binding modes of the ligands in GluK1/GluK2 and the steric repulsion of Asn690 in GluK2. All ligands, regardless of agonist efficacy, induced full domain closure. Consequently, ligand efficacy and domain closure did not directly coincide with DH analogues and the kainate receptors.
PDB ID: 2ZNSDownload
MMDB ID: 72413
PDB Deposition Date: 2008/5/1
Updated in MMDB: 2011/10
Experimental Method:
x-ray diffraction
Resolution: 2  Å
Source Organism:
Similar Structures:
Biological Unit for 2ZNS: monomeric; determined by author and by software (PISA)
Molecular Components in 2ZNS
Label Count Molecule
Protein (1 molecule)
1
Glutamate Receptor, Ionotropic Kainate 1(Gene symbol: GRIK1)
Molecule annotation
Chemical (1 molecule)
1
1
* Click molecule labels to explore molecular sequence information.

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