Biochemical Characterization of the Nuclease StoNurA from the Hyperthermophilic Archaeion Sulfolobus Tokodaii

摘要

A DNA nuclease gene (ST2109) was cloned from the hyperthermophilic archaeon Sulfolobus tokodaii, and expressed in Escherichia coli. The recombinant protein (StoNurA) was purified to homogeneity by affinity chromatography and gel filtration chromatography. Biochemical analysis demonstrated that StoNurA has DNA binding and 5'-3' exonuclease activities on ssDNA. The temperature and pH optima of StoNurA were 65 °C and 7.5, respectively. Divalent cation dependence of StoNurA activities was Mn2+. The half-life of heat inactivation at 100 °C was 5 min. Our data suggest that NurA may play a key function in the processing of DNA recombinational repair.