RT Journal Article SR Electronic(1) A1 Blanco, Ana A1 Díaz, Pilar A1 Zueco, Jesús A1 Parascandola, Palma A1 Pastor, F. I. JavierYR 1999 T1 A multidomain xylanase from a Bacillus sp. with a region homologous to thermostabilizing domains of thermophilic enzymes JF Microbiology, VO 145 IS 8 SP 2163 OP 2170 DO https://doi.org/10.1099/13500872-145-8-2163 PB Microbiology Society, SN 1465-2080, AB The gene xynC encoding xylanase C from Bacillus sp. BP-23 was cloned and expressed in Escherichia coli. The nucleotide sequence of a 3538 bp DNA fragment containing xynC gene was determined, revealing an open reading frame of 3258 bp that encodes a protein of 120567 Da. A comparison of the deduced amino acid sequence of xylanase C with known β-glycanase sequences showed that the encoded enzyme is a modular protein containing three different domains. The central region of the enzyme is the catalytic domain, which shows high homology to family 10 xylanases. A domain homologous to family IX cellulose-binding domains is located in the C-terminal region of xylanase C, whilst the N-terminal region of the enzyme shows homology to thermostabilizing domains found in several thermophilic enzymes. Xylanase C showed an activity profile similar to that of enzymes from mesophilic microorganisms. Maximum activity was found at 45°C, and the enzyme was only stable at 55°C or lower temperatures. Xylotetraose, xylotriose, xylobiose and xylose were the main products from birchwood xylan hydrolysis, whilst the enzyme showed increasing activity on xylo-oligosaccharides of increasing length, indicating that the cloned enzyme is an endoxylanase. A deletion derivative of xylanase C, lacking the region homologous to thermostabilizing domains, was constructed. The truncated enzyme showed a lower optimum temperature for activity than the full-length enzyme, 35°C instead of 45°C, and a reduced thermal stability that resulted in a complete inactivation of the enzyme after 2 h incubation at 55°C., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-145-8-2163