Structural highlights
3ejz is a 6 chain structure with sequence from Escherichia coli and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
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| Ligands: | |
| Related: | 1ots, 2fed, 2fee, 3ejy |
| Gene: | clcA, eriC, yadQ, b0155, JW5012 (Escherichia coli) |
| Resources: | FirstGlance, OCA, RCSB, PDBsum |
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.[1] [2] [3] [4] [5]
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
CLC-ec1, a bacterial homologue of the CLC family's transporter subclass, catalyzes transmembrane exchange of Cl(-) and H(+). Mutational analysis based on the known structure reveals several key residues required for coupling H(+) to the stoichiometric countermovement of Cl(-). E148 (Glu(ex)) transfers protons between extracellular water and the protein interior, and E203 (Glu(in)) is thought to function analogously on the intracellular face of the protein. Mutation of either residue eliminates H(+) transport while preserving Cl(-) transport. We tested the role of Glu(in) by examining structural and functional properties of mutants at this position. Certain dissociable side chains (E, D, H, K, R, but not C and Y) retain H(+)/Cl(-) exchanger activity to varying degrees, while other mutations (V, I, or C) abolish H(+) coupling and severely inhibit Cl(-) flux. Transporters substituted with other nonprotonatable side chains (Q, S, and A) show highly impaired H(+) transport with substantial Cl(-) transport. Influence on H(+) transport of side chain length and acidity was assessed using a single-cysteine mutant to introduce non-natural side chains. Crystal structures of both coupled (E203H) and uncoupled (E203V) mutants are similar to wild type. The results support the idea that Glu(in) is the internal proton-transfer residue that delivers protons from intracellular solution to the protein interior, where they couple to Cl(-) movements to bring about Cl(-)/H(+) exchange.
Intracellular proton-transfer mutants in a CLC Cl-/H+ exchanger.,Lim HH, Miller C J Gen Physiol. 2009 Feb;133(2):131-8. Epub 2009 Jan 12. PMID:19139174[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Iyer R, Iverson TM, Accardi A, Miller C. A biological role for prokaryotic ClC chloride channels. Nature. 2002 Oct 17;419(6908):715-8. PMID:12384697 doi:10.1038/nature01000
- ↑ Accardi A, Miller C. Secondary active transport mediated by a prokaryotic homologue of ClC Cl- channels. Nature. 2004 Feb 26;427(6977):803-7. PMID:14985752 doi:10.1038/nature02314
- ↑ Lobet S, Dutzler R. Ion-binding properties of the ClC chloride selectivity filter. EMBO J. 2006 Jan 11;25(1):24-33. Epub 2005 Dec 8. PMID:16341087
- ↑ Nguitragool W, Miller C. Uncoupling of a CLC Cl-/H+ exchange transporter by polyatomic anions. J Mol Biol. 2006 Sep 29;362(4):682-90. Epub 2006 Aug 14. PMID:16905147 doi:10.1016/j.jmb.2006.07.006
- ↑ Jayaram H, Accardi A, Wu F, Williams C, Miller C. Ion permeation through a Cl--selective channel designed from a CLC Cl-/H+ exchanger. Proc Natl Acad Sci U S A. 2008 Aug 12;105(32):11194-9. Epub 2008 Aug 4. PMID:18678918
- ↑ Lim HH, Miller C. Intracellular proton-transfer mutants in a CLC Cl-/H+ exchanger. J Gen Physiol. 2009 Feb;133(2):131-8. Epub 2009 Jan 12. PMID:19139174 doi:10.1085/jgp.200810112
