title: Characterization of two β-xylosidases from Bifidobacterium adolescentis and their contribution to the hydrolysis of prebiotic xylooligosaccharides.
abstract: Xylooligosaccharides have strong bifidogenic properties and are increasingly used as a prebiotic. Nonetheless, little is known about the degradation of these substrates by bifidobacteria. We characterized two recombinant β-xylosidases, XylB and XylC, with different substrate specificities from Bifidobacterium adolescentis. XylB is a novel β-xylosidase that belongs to the recently introduced glycoside hydrolase family 120. In contrast to most reported β-xylosidases, it shows only weak activity on xylobiose and prefers xylooligosaccharides with a degree of polymerization above two. The remaining xylobiose is efficiently hydrolyzed by the second B. adolescentis β-xylosidase, XylC, a glycoside hydrolase of family 43. Furthermore, XylB releases more xylose from arabinose-substituted xylooligosaccharides than XylC (30% and 20%, respectively). The different specificities of XylB, XylC, and the recently described reducing-end xylose-releasing exo-oligoxylanase RexA show how B. adolescentis can efficiently degrade prebiotic xylooligosaccharides.
authors.affiliation: Division of Gene Technology, Katholieke Universiteit Leuven, Belgium.
authors.forename: Stijn
authors.initials: S
authors.lastname: Lagaert
authors.forename: Annick
authors.initials: A
authors.lastname: Pollet
authors.forename: Jan A
authors.initials: JA
authors.lastname: Delcour
authors.forename: Rob
authors.initials: R
authors.lastname: Lavigne
authors.forename: Christophe M
authors.initials: CM
authors.lastname: Courtin
authors.forename: Guido
authors.initials: G
authors.lastname: Volckaert
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001644:Bifidobacterium / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D004795:Enzyme Stability; D006868:Hydrolysis; D007700:Kinetics; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism; D056692:Prebiotics / Q000032:analysis*; D013379:Substrate Specificity; D014994:Xylose / Q000737:chemistry* / Q000378:metabolism; D014995:Xylosidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D009844:Oligosaccharides; D056692:Prebiotics; D014994:Xylose; D014995:Xylosidases