Purification and properties of Aquifex aeolicus DNA polymerase expressed in Escherichia coli.

Abstract

The gene encoding Aquifex aeolicus (Aae) DNA polymerase was expressed under the control of the trp promoter on a high-copy plasmid, pTRPNS, in Escherichia coli. The expressed enzyme was purified 11-fold with a 13.8% yield and a specific activity of 2268.3 U mg(-1). The optimum pH of the enzyme was 6.8-7.2. The optimal concentrations of KCl and Mg(2+) were 20-30 mM and 4-5 mM, respectively. Aae DNA polymerase contained a double-strand-dependent 3'-->5' proofreading exonuclease activity but lacked any detectable 5'-->3' exonuclease activity.