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1iit
From Proteopedia
(New page: 200px<br /><applet load="1iit" size="450" color="white" frame="true" align="right" spinBox="true" caption="1iit, resolution 1.90Å" /> '''GLUR0 LIGAND BINDING...) |
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| - | [[Image:1iit.gif|left|200px]]<br /><applet load="1iit" size=" | + | [[Image:1iit.gif|left|200px]]<br /><applet load="1iit" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1iit, resolution 1.90Å" /> | caption="1iit, resolution 1.90Å" /> | ||
'''GLUR0 LIGAND BINDING CORE COMPLEX WITH L-SERINE'''<br /> | '''GLUR0 LIGAND BINDING CORE COMPLEX WITH L-SERINE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | High-resolution structures of the ligand binding core of GluR0, a | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1IIT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Synechocystis_sp. Synechocystis sp.] with SER as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1IIT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Synechocystis_sp. Synechocystis sp.] with <scene name='pdbligand=SER:'>SER</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IIT OCA]. |
==Reference== | ==Reference== | ||
| Line 14: | Line 14: | ||
[[Category: Synechocystis sp.]] | [[Category: Synechocystis sp.]] | ||
[[Category: Gouaux, E.]] | [[Category: Gouaux, E.]] | ||
| - | [[Category: Mayer, M | + | [[Category: Mayer, M L.]] |
[[Category: Olson, R.]] | [[Category: Olson, R.]] | ||
[[Category: SER]] | [[Category: SER]] | ||
| Line 20: | Line 20: | ||
[[Category: same fold as pbps]] | [[Category: same fold as pbps]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:12:22 2008'' |
Revision as of 11:12, 21 February 2008
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GLUR0 LIGAND BINDING CORE COMPLEX WITH L-SERINE
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.
About this Structure
1IIT is a Single protein structure of sequence from Synechocystis sp. with as ligand. 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 Thu Feb 21 13:12:22 2008
