2ht4: Difference between revisions
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[[Image:2ht4.gif|left|200px]] | [[Image:2ht4.gif|left|200px]] | ||
'''Structure of the Escherichia coli ClC chloride channel Y445W mutant and Fab complex''' | {{Structure | ||
|PDB= 2ht4 |SIZE=350|CAPTION= <scene name='initialview01'>2ht4</scene>, resolution 3.20Å | |||
|SITE= | |||
|LIGAND= <scene name='pdbligand=BR:BROMIDE ION'>BR</scene> | |||
|ACTIVITY= | |||
|GENE= clcA, eriC ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli]) | |||
}} | |||
'''Structure of the Escherichia coli ClC chloride channel Y445W mutant and Fab complex''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
2HT4 is a [ | 2HT4 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] and [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HT4 OCA]. | ||
==Reference== | ==Reference== | ||
Synergism between halide binding and proton transport in a CLC-type exchanger., Accardi A, Lobet S, Williams C, Miller C, Dutzler R, J Mol Biol. 2006 Sep 29;362(4):691-9. Epub 2006 Aug 2. PMID:[http:// | Synergism between halide binding and proton transport in a CLC-type exchanger., Accardi A, Lobet S, Williams C, Miller C, Dutzler R, J Mol Biol. 2006 Sep 29;362(4):691-9. Epub 2006 Aug 2. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/16949616 16949616] | ||
[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Mus musculus]] | [[Category: Mus musculus]] | ||
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[[Category: Williams, C.]] | [[Category: Williams, C.]] | ||
[[Category: BR]] | [[Category: BR]] | ||
[[Category: clc family of channel and | [[Category: clc family of channel and transporter]] | ||
[[Category: fab complex]] | [[Category: fab complex]] | ||
[[Category: h+/cl- antiporter]] | [[Category: h+/cl- antiporter]] | ||
[[Category: membrane protein]] | [[Category: membrane protein]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 17:21:14 2008'' | ||
Revision as of 18:21, 20 March 2008
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| , resolution 3.20Å | |||||||
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| Ligands: | |||||||
| Gene: | clcA, eriC (Escherichia coli) | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Structure of the Escherichia coli ClC chloride channel Y445W mutant and Fab complex
OverviewOverview
The Cl-/H+ exchange-transporter CLC-ec1 mediates stoichiometric transmembrane exchange of two Cl- ions for one proton. A conserved tyrosine residue, Y445, coordinates one of the bound Cl- ions visible in the structure of this protein and is located near the intersection of the Cl- and H+ pathways. Mutants of this tyrosine were scrutinized for effects on the coupled transport of Cl- and H+ determined electrophysiologically and on protein structure determined crystallographically. Despite the strong conservation of Y445 in the CLC family, substitution of F or W at this position preserves wild-type transport behavior. Substitution by A, E, or H, however, produces uncoupled proteins with robust Cl- transport but greatly impaired movement of H+. The obligatory 2 Cl-/1 H+ stoichiometry is thus lost in these mutants. The structures of all the mutants are essentially identical to wild-type, but apparent anion occupancy in the Cl- binding region correlates with functional H+ coupling. In particular, as determined by anomalous diffraction in crystals grown in Br-, an electrophysiologically competent Cl- analogue, the well-coupled transporters show strong Br- electron density at the "inner" and "central" Cl- binding sites. However, in the uncoupled mutants, Br- density is absent at the central site, while still present at the inner site. An additional mutant, Y445L, is intermediate in both functional and structural features. This mutant clearly exchanges H+ for Cl-, but at a reduced H+-to-Cl- ratio; likewise, both the central and inner sites are occupied by Br-, but the central site shows lower Br- density than in wild-type (or in Y445F,W). The correlation between proton coupling and central-site occupancy argues that halide binding to the central transport site somehow facilitates movement of H+, a synergism that is not readily understood in terms of alternating-site antiport schemes.
About this StructureAbout this Structure
2HT4 is a Single protein structure of sequence from Escherichia coli and Mus musculus. Full crystallographic information is available from OCA.
ReferenceReference
Synergism between halide binding and proton transport in a CLC-type exchanger., Accardi A, Lobet S, Williams C, Miller C, Dutzler R, J Mol Biol. 2006 Sep 29;362(4):691-9. Epub 2006 Aug 2. PMID:16949616
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