title: Oligosaccharide binding proteins from Bifidobacterium longum subsp. infantis reveal a preference for host glycans.
abstract: Bifidobacterium longum subsp. infantis (B. infantis) is a common member of the infant intestinal microbiota, and it has been characterized by its foraging capacity for human milk oligosaccharides (HMO). Its genome sequence revealed an overabundance of the Family 1 of solute binding proteins (F1SBPs), part of ABC transporters and associated with the import of oligosaccharides. In this study we have used the Mammalian Glycan Array to determine the specific affinities of these proteins. This was correlated with binding protein expression induced by different prebiotics including HMO. Half of the F1SBPs in B. infantis were determined to bind mammalian oligosaccharides. Their affinities included different blood group structures and mucin oligosaccharides. Related to HMO, other proteins were specific for oligomers of lacto-N-biose (LNB) and polylactosamines with different degrees of fucosylation. Growth on HMO induced the expression of specific binding proteins that import HMO isomers, but also bind blood group and mucin oligosaccharides, suggesting coregulated transport mechanisms. The prebiotic inulin induced other family 1 binding proteins with affinity for intestinal glycans. Most of the host glycan F1SBPs in B. infantis do not have homologs in other bifidobacteria. Finally, some of these proteins were found to be adherent to intestinal epithelial cells in vitro. In conclusion, this study represents further evidence for the particular adaptations of B. infantis to the infant gut environment, and helps to understand the molecular mechanisms involved in this process.
authors.affiliation: Department of Food Science and Technology, University of California Davis, Davis, California, United States of America.
authors.forename: Daniel
authors.initials: D
authors.lastname: Garrido
authors.forename: Jae Han
authors.initials: JH
authors.lastname: Kim
authors.forename: J Bruce
authors.initials: JB
authors.lastname: German
authors.forename: Helen E
authors.initials: HE
authors.lastname: Raybould
authors.forename: David A
authors.initials: DA
authors.lastname: Mills
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001644:Bifidobacterium / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018938:Caco-2 Cells; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006801:Humans; D007444:Inulin / Q000494:pharmacology; D018613:Microscopy, Confocal; D008895:Milk, Human / Q000737:chemistry; D009844:Oligosaccharides / Q000737:chemistry / Q000494:pharmacology; D011134:Polysaccharides / Q000378:metabolism*; D056692:Prebiotics; D011485:Protein Binding / Q000187:drug effects; D040901:Proteomics; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D009844:Oligosaccharides; D011134:Polysaccharides; D056692:Prebiotics; D011956:Receptors, Cell Surface; C055213:saccharide-binding proteins; D007444:Inulin