Abstract
A Clostridium thermocellum gene, xynX, coding for a xylanase was cloned and the complete nucleotide sequence was determined. The xylanase gene of Clostridium thermocellum consists of an ORF of 3261 nucleotide encoding a xylanase (XynX) of 1087 amino acid residues (116 kDa). Sequence analysis of XynX showed a multidomain structure that consisted of four different domains: an N-terminal thermostabilizing domain homologous to sequences found in several thermophilic enzymes, a catalytic domain homologous to family 10 glycosyl hydrolases, a duplicated cellulose-binding domain (CBD) homologous to family IX CBDs, and a triplicated S-layer homologous domain. A deletion mutant of xynX having only the catalytic region produced a mutant enzyme XynX-C which retained catalytic activity but lost thermostability. In terms of half-life at 70 °C, the thermostability of XynX-C was about six times lower than that of the other mutant enzyme, XynX-TC, produced by a mutant containing both the thermostabilizing domain and the catalytic domain. The optimum temperature of XynX-C was about 5–10 °C lower than that of XynX-TC.
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Received: 12 January 2000 / Received revision: 24 April 2000 / Accepted: 1 May 2000
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Kim, H., Jung, K. & Pack, M. Molecular characterization of xynX, a gene encoding a multidomain xylanase with a thermostabilizing domain from Clostridium thermocellum . Appl Microbiol Biotechnol 54, 521–527 (2000). https://doi.org/10.1007/s002530000412
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DOI: https://doi.org/10.1007/s002530000412