Saci_1816: A Trehalase that Catalyzes Trehalose Degradation in the Thermoacidophilic Crenarchaeon Sulfolobus acidocaldarius
2018
Lee, J., Pusan National University, Busan, Republic of Korea | Lee, A., Pusan National University, Busan, Republic of Korea | Moon, K., Pusan National University, Busan, Republic of Korea | Choi, K.H., Pusan National University, Busan, Republic of Korea | Cha, J., Pusan National University, Busan, Republic of Korea
Previously, a cytosolic trehalase (TreH) from the hyperthermophilic archaeon Sulfolobus acidocaldarius was reported; however, the gene responsible for the trehalase activity was not identified. Two genes, saci_1816 and saci_1250, that encode the glycoside hydrolase family 15 type glucoamylase-like proteins in S. acidocaldarius were targeted and expressed in Escherichia coli, 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℃. The pH dependence of the recombinant enzyme was similar to that of the native enzyme, but its optimal temperature was 20-25℃ 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 S. acidocaldarius. Identification of the treH gene confirms that the degradation of trehalose in Sulfolobus species occurs via the TreH pathway.
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