The bundlin pilin protein of enteropathogenic Escherichia coli is an N-acetyllactosamine-specific lectin

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Abstract
Synthetic N‐acetyllactosamine (LacNAc) glycoside sequences coupled to BSA competitively inhibit enteropathogenic Escherichia coli (EPEC) localized adherence (LA) to human intestinal biopsy specimens and tissue culture cell monolayers. The LacNAc‐specific adhesin appears to be associated with the bundle‐forming pili (BFP) expressed by EPEC during the early stages of colonization. Herein, we report that recombinant bundlin inhibits EPEC LA to HEp‐2 cells and binds to HEp‐2 cells. Recombinant bundlin also binds, with millimolar association constants (K assoc), to synthetic LacNAc‐Benzene and LacNAc‐O(CH2)8CONH2 glycosides as assessed in the gas phase by nanoelectrospray ionization mass spectrometry. Furthermore, LacNAc‐BSA inhibits LA only of EPEC strains that express α bundlin alleles, suggesting putative locations for the LacNAc‐binding pocket in the α bundlin monomer. Collectively, these results suggest that α bundlin possesses lectin‐like properties that are responsible for LacNAc‐specific initial adherence of α bundlin‐expressing EPEC strains to host intestinal epithelial cells.