3det

Structure of the E148A, Y445A doubly ungated mutant of E.coli CLC_Ec1, Cl-/H+ antiporter

spinqualitylabelsall models 3det, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3det is a 6 chain structure with sequence from Escherichia coli K-12 and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.8Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CLCA_ECOLI Proton-coupled chloride transporter. Functions as antiport system and exchanges two chloride ions for 1 proton. Probably acts as an electrical shunt for an outwardly-directed proton pump that is linked to amino acid decarboxylation, as part of the extreme acid resistance (XAR) response. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The CLC family of Cl(-)-transporting proteins includes both Cl(-) channels and Cl(-)/H(+) exchange transporters. CLC-ec1, a structurally known bacterial homolog of the transporter subclass, exchanges two Cl(-) ions per proton with strict, obligatory stoichiometry. Point mutations at two residues, Glu(148) and Tyr(445), are known to impair H(+) movement while preserving Cl(-) transport. In the x-ray crystal structure of CLC-ec1, these residues form putative "gates" flanking an ion-binding region. In mutants with both of the gate-forming side chains reduced in size, H(+) transport is abolished, and unitary Cl(-) transport rates are greatly increased, well above values expected for transporter mechanisms. Cl(-) transport rates increase as side-chain volume at these positions is decreased. The crystal structure of a doubly ungated mutant shows a narrow conduit traversing the entire protein transmembrane width. These characteristics suggest that Cl(-) flux through uncoupled, ungated CLC-ec1 occurs via a channel-like electrodiffusion mechanism rather than an alternating-exposure conformational cycle that has been rendered proton-independent by the gate mutations. Ion permeation through a Cl--selective channel designed from a CLC Cl-/H+ exchanger.,Jayaram H, Accardi A, Wu F, Williams C, Miller C Proc Natl Acad Sci U S A. 2008 Aug 12;105(32):11194-9. Epub 2008 Aug 4. PMID:18678918 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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