Binding of CFA/I pili of enterotoxigenic Escherichia coli to asialo-GM1 is mediated by the minor pilin CfaE

T.P.V. Madhavan, J.D. Riches, M.J. Scanlon, G.C. Ulett, Harry Sakellaris

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    9 Citations (Scopus)


    © 2016, American Society for Microbiology. All Rights Reserved. CFA/I pili are representatives of a large family of related pili that mediate the adherence of enterotoxigenic Escherichia coli to intestinal epithelial cells. They are assembled via the alternate chaperone-usher pathway and consist of two subunits, CfaB, which makes up the pilus shaft and a single pilus tip-associated subunit, CfaE. The current model of pilus-mediated adherence proposes that CFA/I has two distinct binding activities; the CfaE subunit is responsible for binding to receptors of unknown structure on erythrocyte and intestinal epithelial cell surfaces, while CfaB binds to various glycosphingolipids, including asialo- GM1. In this report, we present two independent lines of evidence that, contrary to the existing model, CfaB does not bind to asialo-GM1 independently of CfaE. Neither purified CfaB subunits nor CfaB assembled into pili bind to asialo-GM1. Instead, we demonstrate that binding activity toward asialo-GM1 resides in CfaE and this is essential for pilus binding to Caco-2 intestinal epithelial cells. We conclude that the binding activities of CFA/I pili for asialo-GM1, erythrocytes, and intestinal cells are inseparable, require the same amino acid residues in CfaE, and therefore depend on the same or very similar binding mechanisms.
    Original languageEnglish
    Pages (from-to)1642-1649
    Number of pages8
    JournalInfection and Immunity
    Issue number5
    Publication statusPublished - 1 May 2016


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