6v2j

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Crystal structure of ClC-ec1 triple mutant (E113Q, E148Q, E203Q)

Structural highlights

6v2j is a 1 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 2.62Å
Ligands:CL
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.[1] [2] [3] [4] [5]

Publication Abstract from PubMed

Among coupled exchangers, CLCs uniquely catalyze the exchange of oppositely charged ions (Cl(-) for H(+)). Transport-cycle models to describe and explain this unusual mechanism have been proposed based on known CLC structures. While the proposed models harmonize with many experimental findings, gaps and inconsistencies in our understanding have remained. One limitation has been that global conformational change - which occurs in all conventional transporter mechanisms - has not been observed in any high-resolution structure. Here, we describe the 2.6 A structure of a CLC mutant designed to mimic the fully H(+)-loaded transporter. This structure reveals a global conformational change to improve accessibility for the Cl(-) substrate from the extracellular side and new conformations for two key glutamate residues. Together with DEER measurements, MD simulations, and functional studies, this new structure `provides evidence for a unified model of H(+) /Cl(-) transport that reconciles existing data on all CLC-type proteins.

A CLC-ec1 mutant reveals global conformational change and suggests a unifying mechanism for the Cl(-)/H(+) transport cycle.,Chavan TS, Cheng RC, Jiang T, Mathews II, Stein RA, Koehl A, Mchaourab HS, Tajkhorshid E, Maduke M Elife. 2020 Apr 20;9. pii: 53479. doi: 10.7554/eLife.53479. PMID:32310757[6]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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See Also

References

  1. ↑ 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
  2. ↑ 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
  3. ↑ 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
  4. ↑ 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
  5. ↑ 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
  6. ↑ Chavan TS, Cheng RC, Jiang T, Mathews II, Stein RA, Koehl A, Mchaourab HS, Tajkhorshid E, Maduke M. A CLC-ec1 mutant reveals global conformational change and suggests a unifying mechanism for the Cl(-)/H(+) transport cycle. Elife. 2020 Apr 20;9. pii: 53479. doi: 10.7554/eLife.53479. PMID:32310757 doi:http://dx.doi.org/10.7554/eLife.53479

Contents


PDB ID 6v2j

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OCA

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