Mutagenesis of conserved tryptophan residues within the receptor-binding domain of intimin: influence on binding activity and virulence

Microbiology (Reading). 2002 Mar;148(Pt 3):657-65. doi: 10.1099/00221287-148-3-657.


Intimate bacterial adhesion to intestinal epithelium is a pathogenic mechanism shared by several human and animal enteric pathogens, including enteropathogenic and enterohaemorrhagic Escherichia coli and Citrobacter rodentium. The proteins directly involved in this process are the outer-membrane adhesion molecule intimin and the translocated intimin receptor, Tir. The receptor-binding activity of intimin resides within the carboxy terminus 280 aa (Int280) of the polypeptide. Four tryptophan residues, W117/776, W136/795, W222/881 and W240/899, are conserved within different Int280 molecules that otherwise show considerable sequence variation. In this study the influence of site-directed mutagenesis of each of the four tryptophan residues on intimin-Tir interactions and on intimin-mediated intimate attachment was determined. The mutant intimins were also studied using a variety of in vitro and in vivo infection models. The results show that all the substitutions modulated intimin activity, although some mutations had more profound effects than others.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adhesins, Bacterial / chemistry
  • Adhesins, Bacterial / genetics
  • Adhesins, Bacterial / metabolism*
  • Amino Acid Sequence
  • Animals
  • Bacterial Adhesion
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Line
  • Citrobacter freundii / metabolism*
  • Citrobacter freundii / pathogenicity*
  • Colon / microbiology
  • Disease Models, Animal
  • Enterobacteriaceae Infections / microbiology
  • Enterobacteriaceae Infections / physiopathology
  • Escherichia coli Proteins*
  • Female
  • Humans
  • Mice
  • Mice, Inbred C3H
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed*
  • Receptors, Cell Surface / metabolism*
  • Tryptophan / genetics
  • Virulence


  • Adhesins, Bacterial
  • Carrier Proteins
  • Escherichia coli Proteins
  • Receptors, Cell Surface
  • Tir protein, E coli
  • eaeA protein, E coli
  • Tryptophan