2aem

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{{STRUCTURE_2aem| PDB=2aem | SCENE= }}
{{STRUCTURE_2aem| PDB=2aem | SCENE= }}
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'''Crystal Structures of the MthK RCK Domain'''
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===Crystal Structures of the MthK RCK Domain===
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==Overview==
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MthK is a Ca2+-gated K+ channel from Methanobacterium autotrophicum. The crystal structure of the MthK channel in a Ca2+-bound open state was previously determined at 3.3 A and revealed an octameric gating ring composed of eight intracellular ligand-binding RCK (regulate the conductance of K+) domains. It was suggested that Ca2+ binding regulates the gating ring conformation, which in turn leads to the opening and closing of the channel. However, at 3.3 AA resolution, the molecular details of the structure are not well defined, and many of the conclusions drawn from that structure were hypothetical. Here we have presented high resolution structures of the MthK RCK domain with and without Ca2+ bound from three different crystals. These structures revealed a dimeric architecture of the RCK domain and allowed us to visualize the Ca2+ binding and protein-protein contacts at atomic detail. The dimerization of RCK domains is also conserved in other RCK-regulated K+ channels and transporters, suggesting that the RCK dimer serves as a basic unit in the gating ring assembly. A comparison of these dimer structures confirmed that the dimer interface is indeed flexible as suggested previously. However, the conformational change at the flexible interface is of an extent smaller than the previously hypothesized gating ring movement, and a reconstruction of these dimers into octamers by applying protein-protein contacts at the fixed interface did not generate enclosed gating rings. This indicated that there is a high probability that the previously defined fixed interface may not be fixed during channel gating. In addition to the structural studies, we have also carried out biochemical analyses and have shown that near physiological pH, isolated RCK domains form a stable octamer in solution, supporting the notion that the formation of octameric gating ring is a functionally relevant event in MthK gating. Additionally, our stability studies indicated that Ca2+ binding stabilizes the RCK domains in this octameric state.
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{{ABSTRACT_PUBMED_16227203}}
==About this Structure==
==About this Structure==
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==Reference==
==Reference==
Structures of the MthK RCK domain and the effect of Ca2+ on gating ring stability., Dong J, Shi N, Berke I, Chen L, Jiang Y, J Biol Chem. 2005 Dec 16;280(50):41716-24. Epub 2005 Oct 14. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/16227203 16227203]
Structures of the MthK RCK domain and the effect of Ca2+ on gating ring stability., Dong J, Shi N, Berke I, Chen L, Jiang Y, J Biol Chem. 2005 Dec 16;280(50):41716-24. Epub 2005 Oct 14. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/16227203 16227203]
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Crystal structure and mechanism of a calcium-gated potassium channel., Jiang Y, Lee A, Chen J, Cadene M, Chait BT, MacKinnon R, Nature. 2002 May 30;417(6888):515-22. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12037559 12037559]
[[Category: Methanothermobacter thermautotrophicus]]
[[Category: Methanothermobacter thermautotrophicus]]
[[Category: Single protein]]
[[Category: Single protein]]
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[[Category: Helix-turn-helix]]
[[Category: Helix-turn-helix]]
[[Category: Rossmann fold]]
[[Category: Rossmann fold]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 20:20:41 2008''

Revision as of 17:20, 28 July 2008

Image:2aem.png

Template:STRUCTURE 2aem

Crystal Structures of the MthK RCK Domain

Template:ABSTRACT PUBMED 16227203

About this Structure

2AEM is a Single protein structure of sequence from Methanothermobacter thermautotrophicus. Full crystallographic information is available from OCA.

Reference

Structures of the MthK RCK domain and the effect of Ca2+ on gating ring stability., Dong J, Shi N, Berke I, Chen L, Jiang Y, J Biol Chem. 2005 Dec 16;280(50):41716-24. Epub 2005 Oct 14. PMID:16227203

Crystal structure and mechanism of a calcium-gated potassium channel., Jiang Y, Lee A, Chen J, Cadene M, Chait BT, MacKinnon R, Nature. 2002 May 30;417(6888):515-22. PMID:12037559

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