Structure of the shiga-like toxin I B-pentamer complexed with an analogue of its receptor Gb3

Biochemistry. 1998 Feb 17;37(7):1777-88. doi: 10.1021/bi971806n.


Shiga-like toxin I (SLT-I) is a virulence factor of Escherichia coli strains that cause disease in humans. Like other members of the Shiga toxin family, it consists of an enzymatic (A) subunit and five copies of a binding subunit (the B-pentamer). The B-pentamer binds to a specific glycolipid, globotriaosylceramide (Gb3), on the surface of target cells and thereby plays a crucial role in the entry of the toxin. Here we present the crystal structure at 2.8 A resolution of the SLT-I B-pentamer complexed with an analogue of the Gb3 trisaccharide. The structure reveals a surprising density of binding sites, with three trisaccharide molecules bound to each B-subunit monomer of 69 residues. All 15 trisaccharides bind to one side of the B-pentamer, providing further evidence that this side faces the cell membrane. The structural model is consistent with data from site-directed mutagenesis and binding of carbohydrate analogues, and allows the rational design of therapeutic Gb3 analogues that block the attachment of toxin to cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Toxins / chemistry*
  • Bacterial Toxins / metabolism
  • Bacterial Toxins / toxicity
  • Binding Sites
  • Computer Simulation
  • Crystallography, X-Ray
  • Enterotoxins / chemistry
  • Escherichia coli / chemistry
  • Macromolecular Substances
  • Models, Molecular
  • Protein Conformation
  • Receptors, Cell Surface / chemistry*
  • Receptors, Cell Surface / metabolism
  • Receptors, Cell Surface / physiology
  • Shiga Toxin 1
  • Trihexosylceramides / chemistry*
  • Trihexosylceramides / metabolism
  • Trihexosylceramides / physiology


  • Bacterial Toxins
  • Enterotoxins
  • Macromolecular Substances
  • Receptors, Cell Surface
  • Shiga Toxin 1
  • Trihexosylceramides
  • globotriaosylceramide

Associated data

  • PDB/1BOS