Properties of recombinant trehalose synthase from Deinococcus radiodurans expressed in Escherichia coli

A trehalose synthase gene from Deinococcus radiodurans (DSMZ 20539) containing 1659 bp reading frame encoding 552 amino acids was amplified using PCR. The gene was finally ligated into pET30Ek/LIC vector and expressed after isopropyl β-d-thiogalactopyranoside induction in Escherichia coli (DE3) Rosetta pLysS. The recombinant trehalose synthase (DraTreS) containing a His(6)-tag at the C-terminus was purified by metal affinity chromatography and characterized. The expressed enzyme is a homodimer with molecular mass of 126.9 kDa and exhibits the highest activity of 11.35 U/mg at pH 7.6 and at 30°C. DraTreS activity was almost unchanged after 2 h preincubation at 45°C and pH 7.6, and retained about 56% of maximal value after 8 h incubation at 50°C. The DraTreS was strongly inhibited by Cu(2+), Hg(2+), Zn(2+), Al(3+) and 10 mM Tris. The K(m) value of maltose conversion was 290.7 mM.