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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
Author(s) -
Ejby M.,
Guskov A.,
Pichler M. J.,
Zanten G. C.,
Schoof E.,
Saburi W.,
Slotboom D. J.,
Abou Hachem M.
Publication year - 2019
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14257
Subject(s) - biology , atp binding cassette transporter , oligosaccharide , mannan , biochemistry , bifidobacterium animalis , glycan , lactococcus lactis , transporter , bifidobacterium , microbiology and biotechnology , gene , polysaccharide , glycoprotein , bacteria , genetics , lactobacillus , fermentation , lactic acid
Summary 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 Bl MnBP1 and Bl MnBP2, 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 Bl MnBP1 is up to 2570‐fold higher for disaccharides than Bl MnBP2. Structural analysis revealed a substitution of an asparagine that recognizes the mannosyl at position 2 in Bl MnBP1, by a glycine in Bl MnBP2, which affects substrate affinity. Both substitution types occur in bifidobacterial SBPs, but Bl MnBP1‐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.