Two binding proteins of the ABC transporter that confers growth of Bifidobacterium animalis subsp. lactis ATCC27673 on β-mannan possess distinct manno-oligosaccharide binding profiles

M Ejby, A Guskov, M J Pichler, G C Zanten, E Schoof, W Saburi, D J Slotboom, M Abou Hachem*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

7 Citations (Scopus)
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Abstract

Human gut bifidobacteria rely on ATP-binding cassette (ABC) transporters for oligosaccharide uptake. Multiple oligosaccharide-specific solute binding protein (SBP) genes are occasionally associated with a single ABC transporter, but the significance of this multiplicity remains unclear. Here, we characterize BlMnBP1 and BlMnBP2, the two SBPs associated to the β-manno-oligosaccharide (MnOS) ABC transporter in Bifidobacterium animalis subsp. lactis. Despite similar overall specificity and preference to mannotriose (Kd ≈80 nM), affinity of BlMnBP1 is up to 2570-fold higher for disaccharides than BlMnBP2. Structural analysis revealed a substitution of an asparagine that recognizes the mannosyl at position 2 in BlMnBP1, by a glycine in BlMnBP2, which affects substrate affinity. Both substitution-types occur in bifidobacterial SBPs, but BlMnBP1-like variants prevail in human-gut isolates. B. animalis subsp. lactis ATCC27673 showed growth on gluco- and galactomannans and was able to outcompete a mannan-degrading Bacteroides ovatus strain in co-cultures, attesting the efficiency of this ABC uptake system. By contrast, a strain that lacks this transporter failed to grow on mannan. This study highlights SBP diversification as a possible strategy to modulate oligosaccharide uptake preferences of bifidobacterial ABC-transporters during adaptation to specific ecological niches. Efficient metabolism of galactomannan by distinct bifidobacteria, merits evaluating this plant glycan as a potential prebiotic. This article is protected by copyright. All rights reserved.

Original languageEnglish
Article number14257
Pages (from-to)114-130
Number of pages17
JournalMolecular Microbiology
Volume112
Issue number1
Early online date4-Apr-2019
DOIs
Publication statusPublished - Jul-2019

Keywords

  • GUT MICROBIOTA
  • RUMINOCOCCUS-ALBUS
  • GUAR GUM
  • PHOSPHORYLASES
  • BUTYRATE
  • STRAIN

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