[Purification and characterization of a DNA helicase from the hyperthermophilic archaeon Sulfolobus shibatae]

A DNA helicase from the hyperthermophilic archaeon Sulfolobus shibatae has been purified to homogeneity by column chromatography on Q Seqharose, phosphocellulose P11, heparin agarose, Superdex 200 and phenyl Superose. The purified enzyme shows DNA-stimulated ATPase activity. The molecular mass of the enzyme is approximately 63 kD. The S. shibatae DNA helcase is capable of unwinding a 70 bp duplex DNA flanked by unpaired single-stranded tails at both ends. The helicase activity requires Mg2+ and hydrolysis of ATP, and is inhibited by NaCl at concentrations greater than 200 mmol/L. It has an optimal pH of 6.7. The enzyme is active at temperatures between 40 and 80 degrees C, and the activity peaks at 70 degrees C. The S. shibatae DNA helicase is the first native DNA helicase to be isolated from archaea.