Host protein binding and adhesive properties of H6 and H7 flagella of attaching and effacing Escherichia coli

Ayen L. Erdem, Fabiola Avelino, Juan Xicohtencatl Cortes, and Jorge A. Girón^*

Department of Immunobiology, University of Arizona, 1501 N. Campbell Ave., Tucson, AZ 85724, USA; Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edificio 76, Ciudad Universitaria, Puebla, Pue, Mexico, 72000

^* To whom correspondence should be addressed. Email: jagiron{at}email.arizona.edu.

	Abstract

It had been suggested that the flagella of enteropathogenic (EPEC) and enterohemorrhagic (EHEC) Escherichia coli might contribute to host colonization. In this study, we set out to investigate the adhesive properties of H7 and H6 flagella. We studied the ability of EHEC EDL933 (O157:H7) and EPEC E2348/69 (O127:H6) flagella to bind to bovine mucus, host proteins such as mucins, and extracellular matrix proteins. Through several approaches, we found that H6 and H7 flagella and their flagellin monomers, bind to mucins I and II and to freshly isolated bovine mucus. A genetic approach showed that EHEC and EPEC fliC deletion mutants were significantly less adherent to bovine intestinal tissue in comparison to the parental wild type strains. In addition, we found that EPEC bacteria and H6 flagella, but not EHEC, bound largely, in a dose-dependent manner, to collagen and to lesser extent to laminin and fibronectin. We also report that EHEC O157:H7 strains agglutinate rabbit red blood cells via their flagella, a heretofore unknown phenotype in this pathogroup. Collectively, our data demonstrate that the H6 and H7 flagella possess adhesive properties, particularly the ability to bind mucins, that may contribute to colonization of mucosal surfaces.