This is a family of SusD-like proteins, one member of which, BT1043, is an outer membrane lipoprotein involved in host glycan metabolism. The structures of this and SusD-homologs in the family are dominated by tetratrico peptide repeats that may facilitate association with outer membrane beta-barrel transporters required for glycan uptake. The structure of BT1043 complexed with N-acetyllactosamine reveals that recognition is mediated via hydrogen bonding interactions with the reducing end of beta-N-acetylglucosamine, suggesting a role in binding glycans liberated from the mucin polypeptide. Mammalian distal gut bacteria have an expanded capacity to utilize glycans. In the absence of dietary sources, some species rely on host-derived mucosal glycans. The ability of Bacteroides thetaiotaomicron, a prominent human gut symbiont, to forage host glycans contributes to both its ability to persist within an individual host and its ability to be transmitted naturally to new hosts at birth.