title: A beta-glucosidase/xylosidase from the phytopathogenic oomycete, Phytophthora infestans.
abstract: An 85-kDa beta-glucosidase/xylosidase (BGX1) was purified from the axenically grown phytopathogenic oomycete, Phytophthora infestans. The bgx1 gene encodes a predicted 61-kDa protein product which, upon removal of a 21 amino acid leader peptide, accumulates in the apoplastic space. Extensive N-mannosylation accounts for part of the observed molecular mass difference. BGX1 belongs to family 30 of the glycoside hydrolases and is the first such oomycete enzyme deposited in public databases. The bgx1 gene was found in various Phytophthora species, but is apparently absent in species of the related genus, Pythium. Despite significant sequence similarity to human and murine lysosomal glucosylceramidases, BGX1 demonstrated neither glucocerebroside nor galactocerebroside-hydrolyzing activity. The native enzyme exhibited glucohydrolytic activity towards 4-methylumbelliferyl (4-MU) beta-D-glucopyranoside and, to lesser extent, towards 4-MU-D-xylopyranoside, but not towards 4-MU-beta-D-glucopyranoside. BGX1 did not hydrolyze carboxymethyl cellulose, cellotetraose, chitosan or xylan, suggesting high substrate specificity and/or specific cofactor requirements for enzymatic activity.
authors.affiliation: Institut für Pflanzenbiochemie, Abteilung Stress- und Entwicklungsbiologie, Weinberg 3, D-06120, Halle/Saale, Germany.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Brunner
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wirtz
authors.forename: Jocelyn K C
authors.initials: JK
authors.lastname: Rose
authors.forename: Alan G
authors.initials: AG
authors.lastname: Darvill
authors.forename: Francine
authors.initials: F
authors.lastname: Govers
authors.forename: Dierk
authors.initials: D
authors.lastname: Scheel
authors.forename: Thorsten
authors.initials: T
authors.lastname: Nürnberger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D001483:Base Sequence; D004271:DNA, Fungal / Q000032:analysis; D005960:Glucosides / Q000378:metabolism*; D005962:Glucosylceramidase / Q000235:genetics; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006801:Humans; D006923:Hymecromone / Q000031:analogs & derivatives* / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009868:Oomycetes / Q000201:enzymology*; D013045:Species Specificity; D013379:Substrate Specificity; D014995:Xylosidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001617:beta-Glucosidase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004271:DNA, Fungal; D005960:Glucosides; C014110:4-methylumbelliferyl glucoside; D006923:Hymecromone; D006026:Glycoside Hydrolases; D014995:Xylosidases; D001617:beta-Glucosidase; C092512:BgxA protein, Erwinia chrysanthemi; D005962:Glucosylceramidase