Improvement of thermostability and catalytic efficiency of glucoamylase from Talaromyces leycettanus JCM12802 via site-directed mutagenesis to enhance industrial saccharification applications

文献类型： 外文期刊

第一作者： Tong, Lige

作者： Tong, Lige;Zheng, Jie;Wang, Xiao;Wang, Xiaolu;Huang, Huoqing;Yang, Haomeng;Tu, Tao;Wang, Yuan;Bai, Yingguo;Yao, Bin;Luo, Huiying;Qin, Xing

作者机构：

关键词： Glucoamylase; Thermostability; Catalytic efficiency; Site-directed mutagenesis; Industrial application

期刊名称：BIOTECHNOLOGY FOR BIOFUELS （ 影响因子：6.04； 五年影响因子：6.485 ）

ISSN：

年卷期： 2021 年 14 卷 1 期

页码：

收录情况： SCI

摘要： Background Glucoamylase is an important industrial enzyme in the saccharification of starch into glucose. However, its poor thermostability and low catalytic efficiency limit its industrial saccharification applications. Therefore, improving these properties of glucoamylase is of great significance for saccharification in the starch industry. Results In this study, a novel glucoamylase-encoding gene TlGa15B from the thermophilic fungus Talaromyces leycettanus JCM12802 was cloned and expressed in Pichia pastoris. The optimal temperature and pH of recombinant TlGa15B were 65 celcius and 4.5, respectively. TlGa15B exhibited excellent thermostability at 60 celcius. To further improve thermostability without losing catalytic efficiency, TlGa15B-GA1 and TlGa15B-GA2 were designed by introducing disulfide bonds and optimizing residual charge-charge interactions in a region distant from the catalytic center. Compared with TlGa15B, mutants showed improved optimal temperature, melting temperature, specific activity, and catalytic efficiency. The mechanism underlying these improvements was elucidated through molecular dynamics simulation and dynamics cross-correlation matrices analysis. Besides, the performance of TlGa15B-GA2 was the same as that of the commercial glucoamylase during saccharification. Conclusions We provide an effective strategy to simultaneously improve both thermostability and catalytic efficiency of glucoamylase. The excellent thermostability and high catalytic efficiency of TlGa15B-GA2 make it a good candidate for industrial saccharification applications.

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