Saci_1816: A Trehalase that Catalyzes Trehalose Degradation in the Thermoacidophilic Crenarchaeon .

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.