Cloning, Sequencing, and Expression of the Gene Encoding an Intracellular β-D-Xylosidase from Streptomyces thermoviolaceus OPC-520(Biochemistry & Molecular Biology)

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The intracellular β-xylosidase was induced when Streptomyces thermoviolaceus OPC-520 was grown at 50℃ in a minimal medium containing xylan or xylo-oligosaccharides. The 82-kDa protein with β-xylosidase activity was partially purified and its N-terminal amino acid sequence was analyzed. The gene encoding the enzyme was cloned, sequenced, and expressed in Escherichia coli. The bxlA gene consists of a 2,100-bp open reading frame encoding 770 amino acids. The deduced amino acid sequence of the bxlA gene product had significant similarity with β-xylosidases classified into family 3 of glycosyl hydrolases. The bxlA gene was expressed in E. coli, and the recombinant protein was purified to homogeneity. The enzyme was a monomer with a molecular mass of 82 kDa. The purified enzyme showed hydrolytic activity towards only p-nitrophenyl-β-D-xylopyranoside among the synthetic glycosides tested. Thin-layer chromatography analysis showed that the enzyme is an exo-type enzyme that hydrolyze xylo-oligosaccharides, but had no activity toward xylan. High activity against pNPX occurred in the pH range 6.0-7.0 and temperature range 40-50℃.
社団法人日本農芸化学会の論文
2001-08-23