PMID:11722900

Citation	La Grange, DC, Pretorius, IS, Claeyssens, M and van Zyl, WH (2001) Degradation of xylan to D-xylose by recombinant Saccharomyces cerevisiae coexpressing the Aspergillus niger beta-xylosidase (xlnD) and the Trichoderma reesei xylanase II (xyn2) genes. Appl. Environ. Microbiol. 67:5512-9
Abstract	The beta-xylosidase-encoding xlnD gene of Aspergillus niger 90196 was amplified by the PCR technique from first-strand cDNA synthesized on mRNA isolated from the fungus. The nucleotide sequence of the cDNA fragment was verified to contain a 2,412-bp open reading frame that encodes a 804-amino-acid propeptide. The 778-amino-acid mature protein, with a putative molecular mass of 85.1 kDa, was fused in frame with the Saccharomyces cerevisiae mating factor alpha1 signal peptide (MFalpha1(s)) to ensure correct posttranslational processing in yeast. The fusion protein was designated Xlo2. The recombinant beta-xylosidase showed optimum activity at 60 degrees C and pH 3.2 and optimum stability at 50 degrees C. The K(i(app)) value for D-xylose and xylobiose for the recombinant beta-xylosidase was determined to be 8.33 and 6.41 mM, respectively. The XLO2 fusion gene and the XYN2 beta-xylanase gene from Trichoderma reesei, located on URA3-based multicopy shuttle vectors, were successfully expressed and coexpressed in the yeast Saccharomyces cerevisiae under the control of the alcohol dehydrogenase II gene (ADH2) promoter and terminator. These recombinant S. cerevisiae strains produced 1,577 nkat/ml of beta-xylanase activity when expressing only the beta-xylanase and 860 nkat/ml when coexpressing the beta-xylanase with the beta-xylosidase. The maximum beta-xylosidase activity was 5.3 nkat/ml when expressed on its own and 3.5 nkat/ml when coexpressed with the beta-xylanase. Coproduction of the beta-xylanase and beta-xylosidase enabled S. cerevisiae to degrade birchwood xylan to D-xylose.
Links	PubMed PMC93337 Online version:10.1128/AEM.67.12.5512-5519.2001
Keywords	Aspergillus niger/enzymology; Aspergillus niger/genetics; Cloning, Molecular; Hydrogen-Ion Concentration; Molecular Sequence Data; Recombinant Fusion Proteins/metabolism; Recombination, Genetic; Saccharomyces cerevisiae/enzymology; Saccharomyces cerevisiae/genetics; Saccharomyces cerevisiae/growth & development; Temperature; Trichoderma/enzymology; Trichoderma/genetics; Xylan Endo-1,3-beta-Xylosidase; Xylans/metabolism; Xylose/metabolism; Xylosidases/genetics; Xylosidases/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ASPNG:XYND		GO:0030163: protein catabolic process	ECO:0000314:		P		Figure 3	complete CACAO 8851
ASPNG:XYND		GO:0045493: xylan catabolic process	ECO:0000314:		P		Figure 4	complete CACAO 8852
ASPNG:XYND	involved_in	GO:0045493: xylan catabolic process	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete

References

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