Role of two amino acid residues' insertion on thermal stability of thermophilic alpha-amylase AMY121 from a deep sea bacterium Bacillus sp SCSIO 15121
Role of two amino acid residues' insertion on thermal stability of thermophilic alpha-amylase AMY121 from a deep sea bacterium Bacillus sp SCSIO 15121
复制标题
两个氨基酸残基插入对深海细菌 Bacillus sp SCSIO 15121 嗜热 α-淀粉酶 AMY121 热稳定性的作用
DOI：
10.1007/s00449-014-1330-2
复制
发表时间：
2015
影响因子：
3.8
通讯作者：
Si Zhang
中科院分区：
文献类型：
--
作者：
Lizhen Li;Jian Yang;Jie Li;Lijuan Long;Yunzhu Xiao;Xinpeng Tian;Fazuo Wang;Si Zhang
地衣芽孢杆菌(BLA)和解淀粉芽孢杆菌(BAA)的α-淀粉酶都是重要的工业酶，其结构高度相似，但热稳定性差异显着。这种差异背后的机制仍然知之甚少。在这里，我们研究了两个氨基酸的插入对这两组淀粉酶的热稳定性的作用。新获得的嗜热淀粉酶 AMY121 在一级结构和酶学性质上都更接近 BLA。 BAA组α-淀粉酶中广泛存在的两个氨基酸插入被认为是导致热稳定性差异的关键因素之一，因为来自AMY121的插入突变体（AMY121-EG和AMY121-AA）的热稳定性显着降低，而来自BAA的缺失突变体的热稳定性增加。此外，我们提出插入突变引起的构象紊乱可能会削弱钙结合亲和力，从而降低酶的热稳定性。
α-Amylases fromBacillus licheniformis(BLA) andBacillus amyloliquefaciens(BAA) are both important industrial enzymes with high similarity in structure but significant differences in thermostability. The mechanisms underlying this discrepancy are still poorly understood. Here, we investigated the role of two amino acids’ insertion on the thermostability of these two group amylases. A newly obtained thermophilic amylase AMY121 was found much closer to BLA in both primary structure and enzymological properties. Two amino acids’ insertion widespread among BAA group α-amylases was identified as one of the key factors leading to the thermostability differences, since thermostability of insertion mutants (AMY121-EG and AMY121-AA) from AMY121 significantly decreased, while that of deletion mutant from BAA increased. Moreover, we proposed that conformational disturbance caused by insertion mutation might weaken the calcium-binding affinity and consequently decrease the enzyme thermostability.