Engineering the residual side chains of HAP phytases to improve their pepsin resistance and catalytic efficiency

文献类型： 外文期刊

第一作者： Niu, Canfang

作者： Niu, Canfang;Yang, Peilong;Luo, Huiying;Huang, Huoqing;Wang, Yaru;Yao, Bin

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： 2017 年 7 卷

页码：

收录情况： SCI

摘要： Strong resistance to proteolytic attack is important for feed enzymes. Here, we selected three predicted pepsin cleavage sites, L99, L162, and E230 (numbering from the initiator M of premature proteins), in pepsin-sensitive HAP phytases YkAPPA from Yersinia kristensenii and YeAPPA from Y. enterocolitica, which corresponded to L99, V162, and D230 in pepsin-resistant YrAPPA from Y. rohdei. We constructed mutants with different side chain structures at these sites using site-directed mutagenesis and produced all enzymes in Escherichia coli for catalytic and biochemical characterization. The substitutions E230G/A/P/R/S/T/D, L162G/A/V, L99A, L99A/L162G,and L99A/L162G/E230G improved the pepsin resistance. Moreover, E230G/A and L162G/V conferred enhanced pepsin resistance on YkAPPA and YeAPPA, increased their catalytic efficiency 1.3-2.4-fold, improved their stability at 60 degrees C and pH 1.0-2.0 and alleviated inhibition by metal ions. In addition, E230G increased the ability of YkAPPA and YeAPPA to hydrolyze phytate from corn meal at a high pepsin concentration and low pH, which indicated that optimization of the pepsin cleavage site side chains may enhance the pepsin resistance, improve the stability at acidic pH, and increase the catalytic activity. This study proposes an efficient approach to improve enzyme performance in monogastric animals fed feed with a high phytate content.

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