Summary:
Trehalases play a central role in the metabolism of trehalose and can be found in a wide variety of organisms. A periplasmic trehalase (a, a-trehalose glucohydrolase, EC 3.2.1.28) from the thermophilic bacterium Rhodothermus marinus was purified and the respective encoding gene was identified, cloned and overexpressed in Escherichia coli. The recombinant trehalase is a monomeric protein with a molecular mass of 59 kDa.
Maximum activity was observed at 88C and pH 6.5. The recombinant trehalase exhibited a Km of 0.16 mM and a Vmax of 81 lmol of trehalose (min) 1 (mg of protein) 1 at the optimal temperature for growth of R. marinus (65C) and pH 6.5. The enzyme was highly specific for
trehalose and was inhibited by glucose with a Ki of 7 mM. This is the most thermostable trehalase ever characterized. Moreover, this is the first report on the identification and characterization of a trehalase from a
thermophilic bacterium.