2HLF

Structure of the Escherichis coli ClC chloride channel Y445E mutant and Fab complex


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.30 Å
  • R-Value Free: 0.309 
  • R-Value Work: 0.281 
  • R-Value Observed: 0.282 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Synergism Between Halide Binding and Proton Transport in a CLC-type Exchanger

Accardi, A.Lobet, S.Williams, C.Miller, C.Dutzler, R.

(2006) J Mol Biol 362: 691-699

  • DOI: 10.1016/j.jmb.2006.07.081
  • Primary Citation of Related Structures:  
    2HLF, 2HT4, 2HT3, 2HT2, 2HTL, 2HTK

  • PubMed Abstract: 
  • 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 n ...

    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.


    Organizational Affiliation

    Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02454-9110, USA.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
H(+)/Cl(-) exchange transporter clcAAB444Escherichia coliMutation(s): 1 
Gene Names: clcAeriC
Find proteins for P37019 (Escherichia coli (strain K12))
Explore P37019 
Go to UniProtKB:  P37019
Protein Feature View
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Fab Fragment, Heavy chainCE221Mus musculusMutation(s): 0 
Find proteins for Q4VBH1 (Rattus norvegicus)
Explore Q4VBH1 
Go to UniProtKB:  Q4VBH1
Protein Feature View
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  • Reference Sequence
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Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Fab Fragment, Light chainDF211Mus musculusMutation(s): 0 
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
BR
Query on BR

Download CCD File 
A, B
BROMIDE ION
Br
CPELXLSAUQHCOX-UHFFFAOYSA-M
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.30 Å
  • R-Value Free: 0.309 
  • R-Value Work: 0.281 
  • R-Value Observed: 0.282 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 232.835α = 90
b = 97.593β = 131.52
c = 171.541γ = 90
Software Package:
Software NamePurpose
CNSrefinement
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2006-09-19
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance