title: Cloning of genes encoding alpha-L-arabinofuranosidase and beta-xylosidase from Trichoderma reesei by expression in Saccharomyces cerevisiae.
abstract: A cDNA expression library of Trichoderma reesei RutC-30 was constructed in the yeast Saccharomyces cerevisiae. Two genes, abf1 and bxl1, were isolated by screening the yeast library for extracellular alpha-L-arabinofuranosidase activity with the substrate p-nitrophenyl-alpha-L-arabinofuranoside. The genes abf1 and bxl1 encode 500 and 758 amino acids, respectively, including the signal sequences. The deduced amino acid sequence of ABFI displays high-level similarity to the alpha-L-arabinofuranosidase B of Aspergillus niger, and the two can form a new family of glycosyl hydrolases. The deduced amino acid sequence of BXLI shows similarities to the beta-glucosidases grouped in family 3. The yeast-produced enzymes were tested for enzymatic activities against different substrates. ABFI released L-arabinose from p-nitrophenyl-alpha-L-arabinofuranoside and arabinoxylans and showed some beta-xylosidase activity toward p-nitrophenyl-beta-D-xylopyranoside. BXLI did not release L-arabinose from arabinoxylan. It showed alpha-L-arabinofuranosidase, alpha-L-arabinopyranosidase, and beta-xylosidase activities against p-nitrophenyl-alpha-L-arabinofuranosidase, p-nitrophenyl-alpha-L-arabinopyranoside, and p-nitrophenyl-beta-D- xylopyranoside, respectively, with the last activity being the highest. It was also able to hydrolyze xylobiose and slowly release xylose from polymeric xylan. ABFI and BXLI correspond to a previously purified alpha-L-arabinofuranosidase and a beta-xylosidase from T. reesei, respectively, as confirmed by partial amino acid sequencing of the Trichoderma-produced enzymes. Both enzymes produced in yeasts displayed hydrolytic properties similar to those of the corresponding enzymes purified from T. reesei.
authors.affiliation: VTT Biotechnology and Food Research, Espoo, Finland.
authors.forename: E
authors.initials: E
authors.lastname: Margolles-Clark
authors.forename: M
authors.initials: M
authors.lastname: Tenkanen
authors.forename: T
authors.initials: T
authors.lastname: Nakari-Setälä
authors.forename: M
authors.initials: M
authors.lastname: Penttilä
mesh_terms: D000595:Amino Acid Sequence; D001089:Arabinose / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D015870:Gene Expression; D015723:Gene Library; D005800:Genes, Fungal / Q000235:genetics*; D006026:Glycoside Hydrolases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D016415:Sequence Alignment; D017421:Sequence Analysis; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014242:Trichoderma / Q000201:enzymology / Q000235:genetics*; D014990:Xylans / Q000378:metabolism; D014994:Xylose / Q000378:metabolism; D014995:Xylosidases / Q000235:genetics* / Q000378:metabolism
chemical_list: D014990:Xylans; D014994:Xylose; D001089:Arabinose; D006026:Glycoside Hydrolases; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase; C019713:alpha-N-arabinofuranosidase