2HT2

Structure of the Escherichia coli ClC chloride channel Y445H mutant and Fab complex


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.32 Å
  • R-Value Free: 0.305 
  • R-Value Work: 0.270 

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:  

  • 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

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
H(+)/Cl(-) exchange transporter clcA
A, B
473Escherichia coli (strain K12)Mutation(s): 1 
Gene Names: clcA (eriC, yadQ)
Find proteins for P37019 (Escherichia coli (strain K12))
Go to UniProtKB:  P37019
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Fab fragment, heavy chain
C, E
221Rattus norvegicusMutation(s): 0 
Gene Names: Ighg
Find proteins for Q4VBH1 (Rattus norvegicus)
Go to UniProtKB:  Q4VBH1
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Fab fragment, light chain
D, F
211N/AMutation(s): 0 
Protein Feature View is not available: No corresponding UniProt sequence found.
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
BR
Query on BR

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

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.32 Å
  • R-Value Free: 0.305 
  • R-Value Work: 0.270 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 232.294α = 90.00
b = 96.580β = 131.43
c = 170.557γ = 90.00
Software Package:
Software NamePurpose
DENZOdata reduction
REFMACrefinement
SCALEPACKdata scaling
CNSphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

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