An atp binding cassette transporter mediates the uptake of α-(1,6)-linked dietary oligosaccharides in bifidobacterium and correlates with competitive growth on these substrates

Research output: Contribution to journalArticle

Abstract

The molecular details and impact of oligosaccharide uptake by distinct human gut microbiota (HGM) are currently not well understood. Non-digestible dietary galacto- and gluco-α-(1,6)-oligosaccharides from legumes and starch, respectively, are preferentially fermented by mainly bifidobacteria and lactobacilli in the human gut. Here we show that the solute binding protein (BlG16BP) associated with an ATP binding cassette (ABC) transporter from the probiotic Bifidobacterium animalis subsp. lactis Bl-04 binds α-(1,6)-linked glucosides and galactosides of varying size, linkage, and monosaccharide composition with preference for the trisaccharides raffinose and panose. This preference is also reflected in the α-(1,6)-galactoside uptake profile of the bacterium. Structures of BlG16BP in complex with raffinose and panose revealed the basis for the remarkable ligand binding plasticity of BlG16BP, which recognizes the nonreducing α-(1,6)-diglycoside in its ligands. BlG16BP homologues occur predominantly in bifidobacteria and a few Firmicutes but lack in other HGMs. Among seven bifidobacterial taxa, only those possessing this transporter displayed growth on α-(1,6)-glycosides. Competition assays revealed that the dominant HGM commensal Bacteroides ovatus was out-competed by B. animalis subsp. lactis Bl-04 in mixed cultures growing on raffinose, the preferred ligand for the BlG16BP. By comparison, B. ovatus mono-cultures grew very efficiently on this trisaccharide These findings suggest that the ABC-mediated uptake of raffinose provides an important competitive advantage, particularly against dominant Bacteroides that lack glycan-specific ABC-transporters. This novel insight highlights the role of glycan transport in defining the metabolic specialization of gut bacteria.

Details

Authors
  • Morten Ejby
  • Folmer Fredslund
  • Joakim Mark Andersen
  • Andreja Vujičić Žagar¶
  • Jonas Rosager Henriksen
  • Thomas Lars Andersen
  • Birte Svensson
  • Dirk Jan Slotboom
  • Maher Abou Hachem
Organisations
External organisations
  • Technical University of Denmark
  • University of Groningen
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Microbiology
  • Microbiology in the medical area
Original languageEnglish
Pages (from-to)20220-20231
Number of pages12
JournalJournal of Biological Chemistry
Volume291
Issue number38
Publication statusPublished - 2016 Sep 16
Publication categoryResearch
Peer-reviewedYes