title: N- and C-terminal truncations of a GH10 xylanase significantly increase its activity and thermostability but decrease its SDS resistance.
abstract: XynII from Volvariella volvacea has high sodium dodecyl sulfate (SDS) resistance, with the potential for industrial applications under harsh conditions. It consists of a single glycoside hydrolase family 10 (GH10) catalytic domain but contains an additional unique 10 and 4 amino acid residues at the N- and C-terminus, respectively. In this study, five XynII derivatives with N- and/or C-terminus deletions were constructed to determine the effects of these regions on enzyme activity, substrate specificity, thermostability, and SDS resistance. Our results revealed that N- and/or C-terminal truncations significantly increased enzyme activity and thermostability, but reduced SDS resistance. Specifically, the XynIIΔNC4 mutant had 2.53-fold more catalytic efficiency (k cat/K m) towards beechwood xylan than wild-type and 3.0-fold more thermostability (t 1/2 [55°C]). XynIIΔNC4 displayed 3.33-, 4.38-, 1.37-, and 1.98-fold more activity against xylotriose, xylotetraose, xylopentaose, and xylohexaose, respectively, than XynII did. However, its half-life (t 1/2) in 4 % SDS was only 1.72 h, while that of XynII was 4.65 h. Circular dichroism analysis revealed that deletion of N- and C-terminal segments caused minor changes in secondary structure. Our observations suggest that the extra N- and C-terminal segments in wild-type XynII evolved to strengthen the interaction between these regions of the protein, making the local structure more rigid and reducing structural flexibility. In this way, N- and C-terminal truncations increased the thermostability and activity of XynII on different xylans and linear xylooligosaccharides, but reduced its resistance to SDS.
authors.affiliation: Department of Biological Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Zheng
authors.affiliation: Department of Biological Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China.
authors.forename: Jingxuan
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Biological Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China.
authors.forename: Xingchen
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Biological Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China.
authors.forename: Hang
authors.initials: H
authors.lastname: Hu
authors.affiliation: Department of Biological Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China.
authors.forename: Liangkun
authors.initials: L
authors.lastname: Long
authors.affiliation: Department of Biological Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China.
authors.forename: Kaixiang
authors.initials: K
authors.lastname: Chen
authors.affiliation: Department of Biological Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China. dshaojun@hotmail.com.
authors.forename: Shaojun
authors.initials: S
authors.lastname: Ding
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D000072417:Protein Domains; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013379:Substrate Specificity; D055367:Volvariella / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D014990:Xylans / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D014990:Xylans; D012967:Sodium Dodecyl Sulfate; D043364:Endo-1,4-beta Xylanases
keywords: Catalytic activity; GH10 xylanase; N- and C-terminal truncations; SDS resistance; Thermostability