2fec: Difference between revisions
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[[Image:2fec.gif|left|200px]] | [[Image:2fec.gif|left|200px]] | ||
'''Structure of the E203Q mutant of the Cl-/H+ exchanger CLC-ec1 from E.Coli''' | {{Structure | ||
|PDB= 2fec |SIZE=350|CAPTION= <scene name='initialview01'>2fec</scene>, resolution 3.967Å | |||
|SITE= | |||
|LIGAND= | |||
|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 E203Q mutant of the Cl-/H+ exchanger CLC-ec1 from E.Coli''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
2FEC is a [ | 2FEC is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] and [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2FEC OCA]. | ||
==Reference== | ==Reference== | ||
Separate ion pathways in a Cl-/H+ exchanger., Accardi A, Walden M, Nguitragool W, Jayaram H, Williams C, Miller C, J Gen Physiol. 2005 Dec;126(6):563-70. PMID:[http:// | Separate ion pathways in a Cl-/H+ exchanger., Accardi A, Walden M, Nguitragool W, Jayaram H, Williams C, Miller C, J Gen Physiol. 2005 Dec;126(6):563-70. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/16316975 16316975] | ||
[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
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[[Category: clc-ec1; clca_ecoli; chloride/proton exchange transporter]] | [[Category: clc-ec1; clca_ecoli; chloride/proton exchange transporter]] | ||
''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 16:51:25 2008'' | ||
Revision as of 17:51, 20 March 2008
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| , resolution 3.967Å | |||||||
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| Gene: | clcA, eriC (Escherichia coli) | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Structure of the E203Q mutant of the Cl-/H+ exchanger CLC-ec1 from E.Coli
OverviewOverview
CLC-ec1 is a prokaryotic CLC-type Cl(-)/H+ exchange transporter. Little is known about the mechanism of H+ coupling to Cl-. A critical glutamate residue, E148, was previously shown to be required for Cl(-)/H+ exchange by mediating proton transfer between the protein and the extracellular solution. To test whether an analogous H+ acceptor exists near the intracellular side of the protein, we performed a mutagenesis scan of inward-facing carboxyl-bearing residues and identified E203 as the unique residue whose neutralization abolishes H+ coupling to Cl- transport. Glutamate at this position is strictly conserved in all known CLCs of the transporter subclass, while valine is always found here in CLC channels. The x-ray crystal structure of the E203Q mutant is similar to that of the wild-type protein. Cl- transport rate in E203Q is inhibited at neutral pH, and the double mutant, E148A/E203Q, shows maximal Cl- transport, independent of pH, as does the single mutant E148A. The results argue that substrate exchange by CLC-ec1 involves two separate but partially overlapping permeation pathways, one for Cl- and one for H+. These pathways are congruent from the protein's extracellular surface to E148, and they diverge beyond this point toward the intracellular side. This picture demands a transport mechanism fundamentally different from familiar alternating-access schemes.
About this StructureAbout this Structure
2FEC is a Single protein structure of sequence from Escherichia coli and Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
Separate ion pathways in a Cl-/H+ exchanger., Accardi A, Walden M, Nguitragool W, Jayaram H, Williams C, Miller C, J Gen Physiol. 2005 Dec;126(6):563-70. PMID:16316975
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