1TQQ

Structure of TolC in complex with hexamminecobalt


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.75 Å
  • R-Value Free: 0.305 
  • R-Value Work: 0.264 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structure of the ligand-blocked periplasmic entrance of the bacterial multidrug effllux protein TolC

Higgins, M.K.Eswaran, J.Edwards, P.C.Schertler, G.F.Hughes, C.Koronakis, V.

(2004) J.Mol.Biol. 342: 697-702

  • DOI: 10.1016/j.jmb.2004.07.088

  • PubMed Abstract: 
  • The trimeric TolC protein of Escherichia coli comprises an outer membrane beta-barrel and a contiguous alpha-helical barrel projecting across the periplasm. This provides a single 140 A long pore for multidrug efflux and protein export. We have previ ...

    The trimeric TolC protein of Escherichia coli comprises an outer membrane beta-barrel and a contiguous alpha-helical barrel projecting across the periplasm. This provides a single 140 A long pore for multidrug efflux and protein export. We have previously reported that trivalent cations such as hexammine cobalt can severely inhibit the conductivity of the TolC pore reconstituted in planar lipid bilayers. Here, isothermal calorimetry shows that Co(NH(3))(6)(3+) binds to TolC with an affinity of 20 nM. The crystal structure of the TolC-Co(NH(3))(6)(3+) complex was determined to 2.75 A resolution, and showed no significant difference in the protein when compared with unliganded TolC. An electron density difference map revealed that a single ligand molecule binds at the centre of the periplasmic entrance, the sole constriction of TolC. The octahedral symmetry of the ligand and the three-fold rotational symmetry of the TolC entrance determine a binding site in which the ligand forms hydrogen bonds with the Asp(374) residue of each monomer. When Asp(374) was substituted by alanine, high affinity ligand binding was abolished and inhibition of TolC pore conductivity in lipid bilayers was alleviated. Comparable effects followed independent substitution of the neighbouring Asp(371), indicating that this aspartate ring also contributes to the high affinity ligand binding site. As the electronegative entrance is widely conserved in the TolC family, it may be a useful target for the development of inhibitors against multidrug resistant pathogenic bacteria.


    Organizational Affiliation

    Department of Pathology, Cambridge University, Tennis Court Road, Cambridge CB2 1QP, UK.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Outer membrane protein tolC
A, B, C
471Escherichia coli (strain K12)Mutation(s): 0 
Gene Names: tolC (colE1-i, mtcB, mukA, refI, toc, weeA)
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: BETA-BARREL
Sub Group: 
Beta-Barrel Membrane Proteins: Monomeric/Dimeric
Protein: 
TolC outer membrane protein
Find proteins for P02930 (Escherichia coli (strain K12))
Go to UniProtKB:  P02930
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NCO
Query on NCO

Download SDF File 
Download CCD File 
C
COBALT HEXAMMINE(III)
Co H18 N6
DYLMFCCYOUSRTK-FGTKAUEHAT
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.75 Å
  • R-Value Free: 0.305 
  • R-Value Work: 0.264 
  • Space Group: H 3
Unit Cell:
Length (Å)Angle (°)
a = 265.276α = 90.00
b = 265.276β = 90.00
c = 96.253γ = 120.00
Software Package:
Software NamePurpose
MOLREPphasing
REFMACrefinement
MOSFLMdata reduction
CCP4data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-07-20
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance