Lee Junho, Lee Areum, Moon Keumok, Choi Kyoung-Hwa, Cha Jaeho
Department of Microbiology, College of Natural Sciences, Pusan National University, Busan 46241, Republic of Korea.
Microbiological Resource Research Institute, Pusan National University, Busan 46241, Republic of Korea.
J Microbiol Biotechnol. 2018 Jun 28;28(6):909-916. doi: 10.4014/jmb.1802.02038.
Previously, a cytosolic trehalase (TreH) from the hyperthermophilic archaeon was reported; however, the gene responsible for the trehalase activity was not identified. Two genes, and , that encode the glycoside hydrolase family 15 type glucoamylase-like proteins in were targeted and expressed in , and their abilities to hydrolyze trehalose were examined. Recombinant Saci_1816 hydrolyzed trehalose exclusively without any help from a cofactor. The mass spectrometric analysis of partially purified native TreH also confirmed that Saci_1816 was involved in proteins exhibiting trehalase activity. Optimal trehalose hydrolysis activity of the recombinant Saci_1816 was observed at pH 4.0 and 60°C. The pH dependence of the recombinant enzyme was similar to that of the native enzyme, but its optimal temperature was 20-25°C lower, and its thermostability was also slightly reduced. From the biochemical and structural results, Saci_1816 was identified as a trehalase responsible for trehalose degradation in . Identification of the gene confirms that the degradation of trehalose in species occurs via the TreH pathway.
此前，有报道称从嗜热古菌中发现了一种胞质海藻糖酶（TreH）；然而，负责海藻糖酶活性的基因尚未确定。对编码糖苷水解酶家族15型葡糖淀粉酶样蛋白的两个基因进行了靶向并在中表达，并检测了它们水解海藻糖的能力。重组Saci_1816在没有任何辅助因子的情况下专门水解海藻糖。对部分纯化的天然TreH进行质谱分析也证实，Saci_1816参与了具有海藻糖酶活性的蛋白质。重组Saci_1816在pH 4.0和60°C时观察到最佳海藻糖水解活性。重组酶的pH依赖性与天然酶相似，但其最佳温度低20 - 25°C，热稳定性也略有降低。根据生化和结构结果，Saci_1816被鉴定为负责中海藻糖降解的海藻糖酶。基因的鉴定证实了物种中海藻糖的降解是通过TreH途径发生的。
