文献类型：期刊文献

英文题名：Engineering 7β-Hydroxysteroid Dehydrogenase for Enhanced Ursodeoxycholic Acid Production by Multiobjective Directed Evolution

作者：Zheng, Ming-Min[1];Chen, Ke-Cai[1];Wang, Ru-Feng[1];Li, Hao[1];Li, Chun-Xiu[1];Xu, Jian-He[1,2]

机构：[1]East China Univ Sci & Technol, State Key Lab Bioreactor Engn, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Shanghai Collaborat Innovat Ctr Biomfg Technol, Shanghai 200237, Peoples R China

年份：2017

卷号：65

期号：6

起止页码：1178

外文期刊名：JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

收录：;EI(收录号：20170803369239);WOS:【SCI-EXPANDED(收录号:WOS:000394481900012)】；

基金：This work was financially supported by the National Natural Science Foundation of China (21276082 and 21536004), the Ministry of Science and Technology, P. R. China (2011CB710800, 2011AA02A210, and 2012AA022201), and the Shanghai Commission of Science and Technology (11431921600).

语种：英文

外文关键词：biocatalysis; cascade reaction; 7 beta-hydroxysteroid dehydrogenase; multiobjective directed evolution; ursodeoxycholic acid

摘要：Ursodeoxycholic acid (UDCA) is the main active ingredient of natural bear bile powder with multiple pharmacological functions. 7 beta-Hydroxysteroid dehydrogenase (HSDH) is a key biocatalyst for the synthesis of UDCA. However, all the 7 beta-HSDHs reported commonly suffer from poor activity and thermostability, resulting in limited productivity of UDCA. In this study, a multiobjective directed evolution (MODE) strategy was proposed and applied to improve the activity, thermostability, and pH optimum of a 7 beta-HSDH. The best variant (V3-1) showed a specific activity 5.5-fold higher than and a half-life 3-fold longer than those of the wild type. In addition, the pH optimum of the variant was shifted to a weakly alkaline value. In the cascade reaction, the productivity of UDCA with V3-1 increased to 942 g L-1 day(-1), in contrast to 141 g L-1 day(-1) with the wild type. Therefore, this study provides a useful strategy for improving the catalytic efficiency of a key enzyme that significantly facilitated the bioproduction of UDCA.