Download MendeleyTwo binding proteins of the ABC transporter that confers growth of Bifidobacterium animalis subsp. lactis ATCC27673 on beta-mannan possess distinct manno-oligosaccharide-binding profiles.
Ejby, M., Guskov, A., Pichler, M.J., Zanten, G.C., Schoof, E., Saburi, W., Slotboom, D.J., Abou Hachem, M.(2019) Mol Microbiol 112: 114-130
- PubMed: 30947380
- DOI: https://doi.org/10.1111/mmi.14257
- Primary Citation of Related Structures:
6FUV, 6I5R, 6I5V, 6I5W - PubMed 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 (K d ≈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.
Organizational Affiliation:
Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads building 224, Kgs Lyngby, 2800, Denmark.
