Secretory expression of a β-xylosidase gene from Thermomyces lanuginosus in Escherichia coli and characterization of its recombinant enzyme.
OBJECTIVE
To characterize a β-xylosidase from the thermophilic fungus Thermomyces lanuginosus and to investigate its potential in saccharification of hemicellulosic xylans.


RESULTS
A gene (designated TlXyl43) encoding β-xylosidase was cloned from T. lanuginosus CAU44 and expressed in Escherichia coli. The gene consists of a 1017-bp open reading frame without introns. It encodes a mature protein of 338 residues with no predicted signal peptide, belonging to glycoside hydrolase (GH) family 43. Over 60% of the recombinant β-xylosidase (TlXyl43) was secreted into the culture medium. TlXyl43 was purified 2·6-fold to homogeneity with an estimated mass of 51·6kDa by SDS-PAGE. The purified enzyme exhibited optimal activity at pH 6·5 and 55°C and was stable at 50°C. It was competitively inhibited by xylose with a Ki value of 63mmol l(-1).


CONCLUSIONS
In this study, a GH family 43 β-xylosidase gene (TlXyl43) from T. lanuginosus CAU44 was cloned and functionally expressed in E. coli, and over 60% of recombinant protein was secreted into the culture.


CONCLUSIONS
This is the first report of the cloning and functional expression of a β-xylosidase gene from Thermomyces species. TlXyl43 holds great potential for variety of industries.
Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing, China Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China Qingdao Center for Disease Prevention and Control, Qingdao, China.
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Z
Chen
Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing, China Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China Qingdao Center for Disease Prevention and Control, Qingdao, China.
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H
Jia
Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing, China Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China Qingdao Center for Disease Prevention and Control, Qingdao, China.
Y
Y
Yang
Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing, China Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China Qingdao Center for Disease Prevention and Control, Qingdao, China.
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Q
Yan
Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing, China Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China Qingdao Center for Disease Prevention and Control, Qingdao, China.
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Z
Jiang
Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing, China Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China Qingdao Center for Disease Prevention and Control, Qingdao, China.
C
C
Teng
D000595:Amino Acid Sequence; D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D014990:Xylans / Q000378:metabolism; D014994:Xylose / Q000378:metabolism; D014995:Xylosidases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics*
D011994:Recombinant Proteins; D014990:Xylans; D014994:Xylose; D014995:Xylosidases; C026579:exo-1,4-beta-D-xylosidase