3-Sulfogalactosyl-dependent adhesion of Escherichia coli HS multivalent adhesion molecule is attenuated by sulfatase activity

Bacterial adhesion to host receptors is an early and essential step in bacterial colonization, and the nature of adhesin-receptor interactions determines bacterial localization and thus the outcome of these interactions. Here, we determined the host receptors for the Multivalent Adhesion Molecule (MAM) from the gut commensal E. coli HS (MAMHS), which contains an array of seven mammalian cell entry (MCE) domains. The MAMHS adhesin interacted with a range of host receptors, through recognition of a shared 3-O-sulfo-galactosyl moiety. This functional group is also found in mucin, a component of the intestinal mucus layer and thus one of the prime adherence targets for commensal E. coli. Mucin gels impeded the motility of E. coli by acting as a physical barrier, and the barrier effect was enhanced by specific interactions between mucin and MAMHS in a sulfation-dependent manner. Desulfation of mucin by pure sulfatase or the sulfatase-producing commensal Bacteroides thetaiotaomicron decreased binding of E. coli to mucin and increased the attachment of bacteria to the epithelial surface, via interactions with surface-localized sulfated lipid and protein receptors. Together, our results demonstrate that the E. coli adhesin MAMHS facilitates retention of a gut commensal by attachment to mucin. They further suggest that the amount of sulfatase secreted by mucin-foraging bacteria such as B. thetaiotaomicron, inhabiting the same niche, may affect the capacity of the mucus barrier to retain commensal E. coli.