Identification of carbohydrate structures as receptors for localised adherent enteropathogenic Escherichia coli

Abstract

Enteropathogenic Escherichia coli strains of diffused adherent (DA) and localised adherent (LA) phenotypes were tested for their ability to bind to glycolipids. DA strains did not bind to the glycolipids tested, while LA strains bound to asialo GM₁, asialo GM₂, globoside and lacto-N-neotetraose in decreasing order of avidity. The minimum common sequence among the four glycolipids could be delineated as GalNac β 1-4 Gal as the binding epitope with GalNac β 1-3 Gal and GlcNac β 1-3 Gal serving as relatively weaker binders. The binding was not inhibited by a variety of free oligosaccharides or by the neoglycoproteins tested. Adhesion-negative mutants of an enteropathogenic LA strain showed a markedly reduced binding to asialo GM₁ indicating that the recognition of GalNac β 1-4 Gal was correlated with the ability to adhere to HeLa cells. Thus recognition and binding to glycolipids could play an important role in colonisation through adherence to intestinal surfaces.