A thermophilic phosphatase from Methanothermobacter marburgensis and its application to in vitro biosynthesis.

Phosphatases catalyze the irreversible dephosphorylation of phosphate-containing compounds, and hence can be applied as the final enzymatic step for the synthesis of various biochemicals. However, the extensive substrate spectrums of phosphatases impose a great challenge for efficient biomanufacturing. Characterization of phosphatases is therefore of extreme importance. In this study, MmPase, a putative HAD phosphatase from Methanothermobacter marburgensis , was expressed, purified, and characterized. Recombinant MmPase was readily expressed in Escherichia coli , and required metal ions such as Mn2+ or Mg2+ to function. MmPase worked optimally at 50 °C, pH 6.5, and exhibited a half-life of 6.5 h under this condition. Among all substrates tested, MmPase established the highest dephosphorylation activity against D -tagatose 6-phosphate, and was relatively specific for this substrate than for D -glucose 1-phosphate, D -glucose 6-phosphate, and D -fructose 6-phosphate. Therefore, MmPase was integrated into an in vitro synthetic enzymatic biosystem for the one-pot production of D -tagatose from maltodextrin, and achieved a product yield of 37.6%. Our studies of MmPase provided a promising strategy for the economic and efficient production of D -tagatose in the future. • We examined the enzymatic properties of a putative phosphatase from M. marburgensis. • This enzyme was thermostable and relatively specific for D -tagatose 6-phosphate. • This enzyme was applied in an in vitro synthetic biosystem to produce D -tagatose. [ABSTRACT FROM AUTHOR]