文献类型： 外文期刊

作者： Tu, Tao ¹ ; Li, Yeqing ¹ ; Su, Xiaoyun ¹ ; Meng, Kun ¹ ; Ma, Rui ¹ ; Wang, Yuan ¹ ; Yao, Bin ¹ ; Lin, Zhemin; Luo, Huiyin ¹ ;

作者机构： 1.Chinese Acad Agr Sci, Feed Res Inst, Key Lab Feed Biotechnol, Minist Agr, 12 Zhongguancun South St, Beijing 100081, Peoples R China

2.Chinese Acad Agr Sci, Feed Res Inst, Key Lab Feed Biotechnol, Minist Agr, 12 Zhongguancun Sou

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： Understanding the dynamics of the key pectinase, polygalacturonase, and improving its thermotolerance and catalytic efficiency are of importance for the cost-competitive bioconversion of pectic materials. By combining structure analysis and molecular dynamics (MD) simulations, eight mutagenesis sites having the potential to form cation-pi interactions were identified in the widely used fungal endo-polygalacturonase PG63. In comparison to the wild-type, three single mutants H58Y, T71Y and T304Y showed improved thermostability (the apparent T(m)s increased by 0.6-3.9 degrees C) and catalytic efficiency (by up to 32-fold). Chromatogram analysis of the hydrolysis products indicated that a larger amount of shorter sugars were released from the polygalacturonic acid by these three mutants than by the wild-type. MD analysis of the enzyme-substrate complexes illustrated that the mutants with introduced cation-p interaction have modified conformations of catalytic crevice, which provide an enviable environment for the catalytic process. Moreover, the lower plasticity of T3 loop 2 at the edge of the subsite tunnel appears to recruit the reducing ends of oligogalacturonide into the active site tunnel and initiates new hydrolysis reactions. This study demonstrates the importance of cation-p interaction in protein conformation and provides a realistic strategy to enhance the thermotolerance and catalytic performance of endo-polygalacturonases.