Mutagenesis of conserved tryptophan residues within the receptor-binding domain of intimin: influence on binding activity and virulence
Centre for Molecular Microbiology and Infection 1 and Centre for Structural Biology 3 , Department of Biological Sciences, Imperial College of Science, Technology and Medicine, London SW7 2AZ, UK Centre for Paediatric Gastroenterology, Royal Free Hospital, London NW3 2QG, UK 2 Author for corresponde...
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Veröffentlicht in: | Microbiology (Society for General Microbiology) 2002-03, Vol.148 (3), p.657-665 |
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Zusammenfassung: | Centre for Molecular Microbiology and Infection 1 and Centre for Structural Biology 3 , Department of Biological Sciences, Imperial College of Science, Technology and Medicine, London SW7 2AZ, UK
Centre for Paediatric Gastroenterology, Royal Free Hospital, London NW3 2QG, UK 2
Author for correspondence: Gad Frankel. Tel: +44 20 7594 5253. Fax: +44 20 7594 5255. e-mail: g.frankel{at}ic.ac.uk
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.
Keywords: Citrobacter rodentium , EPEC, EHEC, Tir Abbreviations: A/E lesion, attaching and effacing lesion; EHEC, enterohaemorrhagic Escherichia coli ; EPEC, enteropathogenic Escherichia coli ; FAS, fluorescent actin stain; LEE, locus of enterocyte effacement; MBP, maltose-binding protein; Tir, translocated intimin receptor |
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ISSN: | 1350-0872 1465-2080 |
DOI: | 10.1099/00221287-148-3-657 |