1LTT

LACTOSE BINDING TO HEAT-LABILE ENTEROTOXIN REVEALED BY X-RAY CRYSTALLOGRAPHY


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Work: 0.182 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Lactose binding to heat-labile enterotoxin revealed by X-ray crystallography.

Sixma, T.K.Pronk, S.E.Kalk, K.H.van Zanten, B.A.Berghuis, A.M.Hol, W.G.

(1992) Nature 355: 561-564

  • DOI: 10.1038/355561a0

  • PubMed Abstract: 
  • Recognition of the oligosaccharide portion of ganglioside GM1 in membranes of target cells by the heat-labile enterotoxin from Escherichia coli is the crucial first step in its pathogenesis, as it is for the closely related cholera toxin. These toxin ...

    Recognition of the oligosaccharide portion of ganglioside GM1 in membranes of target cells by the heat-labile enterotoxin from Escherichia coli is the crucial first step in its pathogenesis, as it is for the closely related cholera toxin. These toxins have five B subunits, which are essential for GM1 binding, and a single A subunit, which needs to be nicked by proteolysis and reduced, yielding an A1-'enzyme' and an A2-'linker' peptide. A1 is translocated across the membrane of intestinal epithelial cells, possibly after endocytosis, upon which it ADP-ribosylates the G protein Gs alpha. The mechanism of binding and translocation of these toxins has been extensively investigated, but how the protein is orientated on binding is still not clear. Knowing the precise arrangement of the ganglioside binding sites of the toxins will be useful for designing drugs against the diarrhoeal diseases caused by organisms secreting these toxins and in the development of oral vaccines against them. We present here the three-dimensional structure of the E. coli heat-labile enterotoxin complexed with lactose. This reveals the location of the binding site of the terminal galactose of GM1, which is consistent with toxin binding to the target cell with its A1 fragment pointing away from the membrane. A small helix is identified at the carboxy terminus of A2 which emerges through the central pore of the B subunits and probably comes into contact with the membrane upon binding, whereas the A1 subunit is flexible with respect to the B pentamer.


    Related Citations: 
    • Crystal Structure of a Cholera Toxin-Related Heat-Labile Enterotoxin from E. Coli
      Sixma, T.K.,Pronk, S.E.,Kalk, K.H.,Wartna, E.S.,Van Zanten, B.A.M.,Witholt, B.,Hol, W.G.J.
      (1991) Nature 351: 371
    • Refined Structure of E. Coli Heat Labile Enterotoxin, a Close Relative of Cholera Toxin
      Sixma, T.K.,Van Zanten, B.A.M.,Dauter, Z.,Hol, W.G.J.
      (1993) J.Mol.Biol. 230: 890


    Organizational Affiliation

    BIOSON Research Institute, Department of Chemistry, University of Groningen, The Netherlands.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
HEAT-LABILE ENTEROTOXIN, SUBUNIT B
D, E, F, G, H
103Escherichia coliGene Names: eltB (ltpB)
Find proteins for P32890 (Escherichia coli)
Go to UniProtKB:  P32890
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
HEAT-LABILE ENTEROTOXIN, SUBUNIT A
A
185Escherichia coliGene Names: eltA (ltpA)
Find proteins for P06717 (Escherichia coli)
Go to UniProtKB:  P06717
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
HEAT-LABILE ENTEROTOXIN, SUBUNIT A
C
41Escherichia coliGene Names: eltA (ltpA)
Find proteins for P06717 (Escherichia coli)
Go to UniProtKB:  P06717
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
BGC
Query on BGC

Download SDF File 
Download CCD File 
D, E, F, G, H
BETA-D-GLUCOSE
C6 H12 O6
WQZGKKKJIJFFOK-VFUOTHLCSA-N
 Ligand Interaction
GAL
Query on GAL

Download SDF File 
Download CCD File 
D, E, F, G, H
BETA-D-GALACTOSE
C6 H12 O6
WQZGKKKJIJFFOK-FPRJBGLDSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Work: 0.182 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 119.800α = 90.00
b = 101.200β = 90.00
c = 64.200γ = 90.00
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORphasing
X-PLORrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1994-01-31
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance