title: Novel pH-Stable Glycoside Hydrolase Family 3 β-Xylosidase from Talaromyces amestolkiae: an Enzyme Displaying Regioselective Transxylosylation.
abstract: This paper reports on a novel β-xylosidase from the hemicellulolytic fungus Talaromyces amestolkiae. The expression of this enzyme, called BxTW1, could be induced by beechwood xylan and was purified as a glycoprotein from culture supernatants. We characterized the gene encoding this enzyme as an intronless gene belonging to the glycoside hydrolase gene family 3 (GH3). BxTW1 exhibited transxylosylation activity in a regioselective way. This feature would allow the synthesis of oligosaccharides or other compounds not available from natural sources, such as alkyl glycosides displaying antimicrobial or surfactant properties. Regioselective transxylosylation, an uncommon combination, makes the synthesis reproducible, which is desirable for its potential industrial application. BxTW1 showed high pH stability and Cu(2+) tolerance. The enzyme displayed a pI of 7.6, a molecular mass around 200 kDa in its active dimeric form, and Km and Vmax values of 0.17 mM and 52.0 U/mg, respectively, using commercial p-nitrophenyl-β-d-xylopyranoside as the substrate. The catalytic efficiencies for the hydrolysis of xylooligosaccharides were remarkably high, making it suitable for different applications in food and bioenergy industries.
authors.affiliation: Centro de Investigaciones Biológicas (CIB), CSIC, Madrid, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Nieto-Domínguez
authors.affiliation: Centro de Investigaciones Biológicas (CIB), CSIC, Madrid, Spain.
authors.forename: Laura I
authors.initials: LI
authors.lastname: de Eugenio
authors.affiliation: Centro de Investigaciones Biológicas (CIB), CSIC, Madrid, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Barriuso
authors.affiliation: Centro de Investigaciones Biológicas (CIB), CSIC, Madrid, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Prieto
authors.affiliation: Centro de Investigaciones Biológicas (CIB), CSIC, Madrid, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Fernández de Toro
authors.affiliation: Centro de Investigaciones Biológicas (CIB), CSIC, Madrid, Spain.
authors.forename: Ángeles
authors.initials: Á
authors.lastname: Canales-Mayordomo
authors.affiliation: Centro de Investigaciones Biológicas (CIB), CSIC, Madrid, Spain mjmartinez@cib.csic.es.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Martínez
mesh_terms: D003300:Copper / Q000494:pharmacology; D004795:Enzyme Stability; D005965:Glucuronates / Q000378:metabolism; D006027:Glycosides / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008970:Molecular Weight; D009844:Oligosaccharides / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity; D032901:Talaromyces / Q000201:enzymology*; D014994:Xylose / Q000378:metabolism; D014995:Xylosidases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D005965:Glucuronates; D006027:Glycosides; D009844:Oligosaccharides; C570991:xylooligosaccharide; D003300:Copper; D014994:Xylose; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase