Biochemical characterization of two thermostable xylanolytic enzymes encoded by a gene cluster of Caldicellulosiruptor owensensis

Shuofu Mi; Xiaojing Jia; Jinzhi Wang; Weibo Qiao; Xiaowei Peng; Yejun Han

doi:10.1371/journal.pone.0105264

Biochemical characterization of two thermostable xylanolytic enzymes encoded by a gene cluster of Caldicellulosiruptor owensensis

PLoS One. 2014 Aug 15;9(8):e105264. doi: 10.1371/journal.pone.0105264. eCollection 2014.

Authors

Shuofu Mi¹, Xiaojing Jia¹, Jinzhi Wang², Weibo Qiao³, Xiaowei Peng¹, Yejun Han¹

Affiliations

¹ National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China.
² Institute of Agro-food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing, China.
³ National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China; Shenyang Agricultural University, Shenyang, China.

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Sequence
Bacterial Proteins / chemistry*
Bacterial Proteins / genetics
Biocatalysis
Catalytic Domain
Cloning, Molecular
Conserved Sequence
Endo-1,4-beta Xylanases / chemistry*
Endo-1,4-beta Xylanases / genetics
Enzyme Stability
Firmicutes / enzymology*
Firmicutes / genetics
Hydrogen-Ion Concentration
Hydrolysis
Kinetics
Molecular Sequence Data
Multigene Family
Phylogeny
Protein Structure, Quaternary
Sequence Homology, Amino Acid
Xylans / chemistry

Substances

Bacterial Proteins
Xylans
Endo-1,4-beta Xylanases

Grants and funding

YH received funding from National High Technology Research and Development Program of China (863 Project), grant number is 2014AA021905. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.