title: Biochemical characterization of two thermostable xylanolytic enzymes encoded by a gene cluster of Caldicellulosiruptor owensensis.
abstract: The xylanolytic extremely thermophilic bacterium Caldicellulosiruptor owensensis provides a promising platform for xylan utilization. In the present study, two novel xylanolytic enzymes, GH10 endo-β-1,4-xylanase (Coxyn A) and GH39 β-1,4-xylosidase (Coxyl A) encoded in one gene cluster of C.owensensis were heterogeneously expressed and biochemically characterized. The optimum temperature of the two xylanlytic enzymes was 75°C, and the respective optimum pH for Coxyn A and Coxyl A was 7.0 and 5.0. The difference of Coxyn A and Coxyl A in solution was existing as monomer and homodimer respectively, it was also observed in predicted secondary structure. Under optimum condition, the catalytic efficiency (kcat/Km) of Coxyn A was 366 mg ml(-1) s(-1) on beechwood xylan, and the catalytic efficiency (kcat/Km) of Coxyl A was 2253 mM(-1) s(-1) on pNP-β-D-xylopyranoside. Coxyn A degraded xylan to oligosaccharides, which were converted to monomer by Coxyl A. The two intracellular enzymes might be responsible for xylooligosaccharides utilization in C.owensensis, also provide a potential way for xylan degradation in vitro.
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China.
authors.forename: Shuofu
authors.initials: S
authors.lastname: Mi
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Jia
authors.affiliation: Institute of Agro-food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Jinzhi
authors.initials: J
authors.lastname: Wang
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China; Shenyang Agricultural University, Shenyang, China.
authors.forename: Weibo
authors.initials: W
authors.lastname: Qiao
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Peng
authors.affiliation: National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China.
authors.forename: Yejun
authors.initials: Y
authors.lastname: Han
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D055162:Biocatalysis; D020134:Catalytic Domain; D003001:Cloning, Molecular; D017124:Conserved Sequence; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics; D004795:Enzyme Stability; D000068536:Bacillota / Q000201:enzymology* / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D020836:Protein Structure, Quaternary; D017386:Sequence Homology, Amino Acid; D014990:Xylans / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D014990:Xylans; D043364:Endo-1,4-beta Xylanases