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A multidomain xylanase from a Bacillus sp. with a region homologous to thermostabilizing domains of thermophilic enzymes.
Blanco, Ana; Díaz, Pilar; Zueco, Jesús; Parascandola, Palma; Pastor, F I Javier.
Afiliación
  • Blanco A; Department of Microbiology, Faculty of Biology, University of Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain.
  • Díaz P; Department of Microbiology, Faculty of Biology, University of Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain.
  • Zueco J; Department of Micorbiology, Faculty of Pharmacy, University of Valencia, Valencia, Spain.
  • Parascandola P; Department of Chemical and Food Engineering, University of Salerno, Fisciano, Italy.
  • Pastor FIJ; Department of Microbiology, Faculty of Biology, University of Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain.
Microbiology (Reading) ; 145 ( Pt 8): 2163-2170, 1999 Aug.
Article en En | MEDLINE | ID: mdl-10463183
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 120,567 Da. A comparison of the deduced amino acid sequence of xylanase C with known beta-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 micro-organisms. Maximum activity was found at 45 degrees C, and the enzyme was only stable at 55 degrees C 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 degrees C instead of 45 degrees C, and a reduced thermal stability that resulted in a complete inactivation of the enzyme after 2 h incubation at 55 degrees C.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Bacillus / Xilosidasas Idioma: En Revista: Microbiology (Reading) Asunto de la revista: MICROBIOLOGIA Año: 1999 Tipo del documento: Article País de afiliación: España Pais de publicación: Reino Unido
Texto completo
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Bacillus / Xilosidasas Idioma: En Revista: Microbiology (Reading) Asunto de la revista: MICROBIOLOGIA Año: 1999 Tipo del documento: Article País de afiliación: España Pais de publicación: Reino Unido