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Crystal Structure of Human GluK2 Ligand-Binding Core in Complex with Novel Marine-Derived Toxins, Neodysiherbaine A
Structural highlights
DiseaseGRIK2_HUMAN Autosomal recessive non-syndromic intellectual disability. The disease is caused by mutations affecting the gene represented in this entry. FunctionGRIK2_HUMAN Ionotropic glutamate receptor. L-glutamate acts as an excitatory neurotransmitter at many synapses in the central nervous system. Binding of the excitatory neurotransmitter L-glutamate induces a conformation change, leading to the opening of the cation channel, and thereby converts the chemical signal to an electrical impulse. The receptor then desensitizes rapidly and enters a transient inactive state, characterized by the presence of bound agonist. May be involved in the transmission of light information from the retina to the hypothalamus. Modulates cell surface expression of NETO2 (By similarity). Publication Abstract from PubMedDysiherbaine (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. Binding and Selectivity of the Marine Toxin Neodysiherbaine A and Its Synthetic Analogues to GluK1 and GluK2 Kainate Receptors.,Unno M, Shinohara M, Takayama K, Tanaka H, Teruya K, Doh-Ura K, Sakai R, Sasaki M, Ikeda-Saito M J Mol Biol. 2011 Oct 28;413(3):667-83. Epub 2011 Aug 26. PMID:21893069[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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