A β-mannan utilization locus in Bacteroides ovatus involves a GH36 α-galactosidase active on galactomannans

FEBS Lett. 2016 Jul;590(14):2106-18. doi: 10.1002/1873-3468.12250. Epub 2016 Jun 28.


The Bacova_02091 gene in the β-mannan utilization locus of Bacteroides ovatus encodes a family GH36 α-galactosidase (BoGal36A), transcriptionally upregulated during growth on galactomannan. Characterization of recombinant BoGal36A reveals unique properties compared to other GH36 α-galactosidases, which preferentially hydrolyse terminal α-galactose in raffinose family oligosaccharides. BoGal36A prefers hydrolysing internal galactose substitutions from intact and depolymerized galactomannan. BoGal36A efficiently releases (> 90%) galactose from guar and locust bean galactomannans, resulting in precipitation of the polysaccharides. As compared to other GH36 structures, the BoGal36A 3D model displays a loop deletion, resulting in a wider active site cleft which likely can accommodate a galactose-substituted polymannose backbone.

Keywords: Bacteroides ovatus; GH36 α-galactosidase; galactomannan modification; polysaccharide utilization locus.

Publication types

  • Letter

MeSH terms

  • Bacterial Proteins* / genetics
  • Bacterial Proteins* / metabolism
  • Bacteroides* / enzymology
  • Bacteroides* / genetics
  • Galactose / analogs & derivatives
  • Genetic Loci*
  • Mannans / metabolism*
  • Models, Biological*
  • alpha-Galactosidase* / genetics
  • alpha-Galactosidase* / metabolism


  • Bacterial Proteins
  • Mannans
  • galactomannan
  • alpha-Galactosidase
  • Galactose