title: Structural and functional analyses of catalytic domain of GH10 xylanase from Thermoanaerobacterium saccharolyticum JW/SL-YS485.
abstract: Xylanases are capable of decomposing xylans, the major components in plant cell wall, and releasing the constituent sugars for further applications. Because xylanase is widely used in various manufacturing processes, high specific activity, and thermostability are desirable. Here, the wild-type and mutant (E146A and E251A) catalytic domain of xylanase from Thermoanaerobacterium saccharolyticum JW/SL-YS485 (TsXylA) were expressed in Escherichia coli and purified subsequently. The recombinant protein showed optimal temperature and pH of 75°C and 6.5, respectively, and it remained fully active even after heat treatment at 75°C for 1 h. Furthermore, the crystal structures of apo-form wild-type TsXylA and the xylobiose-, xylotriose-, and xylotetraose-bound E146A and E251A mutants were solved by X-ray diffraction to high resolution (1.32-1.66 Å). The protein forms a classic (β/α)8 folding of typical GH10 xylanases. The ligands in substrate-binding groove as well as the interactions between sugars and active-site residues were clearly elucidated by analyzing the complex structures. According to the structural analyses, TsXylA utilizes a double displacement catalytic machinery to carry out the enzymatic reactions. In conclusion, TsXylA is effective under industrially favored conditions, and our findings provide fundamental knowledge which may contribute to further enhancement of the enzyme performance through molecular engineering.
authors.affiliation: Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Han
authors.forename: Jian
authors.initials: J
authors.lastname: Gao
authors.forename: Na
authors.initials: N
authors.lastname: Shang
authors.forename: Chun-Hsiang
authors.initials: CH
authors.lastname: Huang
authors.forename: Tzu-Ping
authors.initials: TP
authors.lastname: Ko
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Chen
authors.forename: Hsiu-Chien
authors.initials: HC
authors.lastname: Chan
authors.forename: Ya-Shan
authors.initials: YS
authors.lastname: Cheng
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhu
authors.forename: Juergen
authors.initials: J
authors.lastname: Wiegel
authors.forename: Wenhua
authors.initials: W
authors.lastname: Luo
authors.forename: Rey-Ting
authors.initials: RT
authors.lastname: Guo
authors.forename: Yanhe
authors.initials: Y
authors.lastname: Ma
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics; D013379:Substrate Specificity; D046950:Thermoanaerobacterium / Q000201:enzymology; D014961:X-Ray Diffraction; D014990:Xylans / Q000737:chemistry*
chemical_list: D011994:Recombinant Proteins; D014990:Xylans; D043364:Endo-1,4-beta Xylanases