Biochemical characterization of extra- and intracellular endoxylanse from thermophilic bacterium Caldicellulosiruptor kronotskyensis

文献类型： 外文期刊

第一作者： Jia, Xiaojing

作者： Jia, Xiaojing;Qiao, Weibo;Peng, Xiaowei;Mi, Shuofu;Su, Hong;Han, Yejun;Jia, Xiaojing;Su, Hong;Tian, Wenli

作者机构：

期刊名称：SCIENTIFIC REPORTS （ 影响因子：4.379； 五年影响因子：5.133 ）

ISSN： 2045-2322

年卷期： 2016 年 6 卷

页码：

收录情况： SCI

摘要： Caldicellulosiruptor kronotskyensis grows on lignocellulosic biomass by the catalysis of intrinsic glycoside hydrolase, and has potential application for consolidated bioprocessing. In current study, two predicted extra-(Xyn10A) and intracellular (Xyn10B) xylanase from C. kronotskyensis were comparatively characterized. Xyn10A and Xyn10B share GH10 catalytic domain with similarity of 41%, while the former contains two tandem N-terminus CBM22s. Xyn10A showed higher hydrolytic capability than Xyn10B on both beechwood xylan (BWX) and oat spelt xylan (OSX). Truncation mutation experiments revealed the importance of CBMs for hydrolytic activity, substrate binding and thermostability of Xyn10A. While the quantity of CBM was not directly related to bind and thermostability. Although CBM was considered to be crucial for substrate binding, Xyn10B and Xyn10A as well as truncations performed similar binding affinity to insoluble substrate OSX. Analysis of point mutation revealed similar key residues, Glu493, Glu601 and Trp658 for Xyn10A and Glu139, Glu247 and Trp305 for Xyn10B. Both Xyn10A and Xyn10B exhibited hydrolytic activity on the mechanical pretreated corncob. After pre-digested by Xyn10A or Xyn10B, the micropores in the the mechanical pretreated corncob were observed, which enhanced the accessibility for cellulase. Compared with corncob hydrolyzed with cellulase alone, enhanced hydrolytic performance of was observed after predigestion by Xyn10A or Xyn10B.

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