1iit

[[Image:1iit.gif|left|200px]]

|PDB= 1iit |SIZE=350|CAPTION= <scene name='initialview01'>1iit</scene>, resolution 1.90&Aring;

|SITE=

|LIGAND= <scene name='pdbligand=SER:SERINE'>SER</scene>

|ACTIVITY=

|GENE= slr1257 GluR0 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1143 Synechocystis sp.])

|DOMAIN=

|RELATEDENTRY=[[1iiw|1IIW]], [[1ii5|1II5]]

|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1iit FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1iit OCA], [http://www.ebi.ac.uk/pdbsum/1iit PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1iit RCSB]</span>

 

 

==Overview==

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.

 

1IIT is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Synechocystis_sp. Synechocystis sp.]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IIT OCA].

 

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:[http://www.ncbi.nlm.nih.gov/pubmed/11518533 11518533]

[[Category: Single protein]]

[[Category: Synechocystis sp.]]

[[Category: Gouaux, E.]]

[[Category: Mayer, M L.]]

[[Category: Olson, R.]]