Biochemical Properties and PCR Performance of a Family B DNA Polymerase from Hyperthermophilic Euryarchaeon Thermococcus peptonophilus

The Thermococcus peptonophilus (Tpe) DNA polymerase gene was expressed under the control of the T7lac promoter on pET-22b(+) in Escherichia coli BL21-CodonPlus(DE3)-RIL in order to fully elucidate its biochemical properties and evaluate its feasibility in polymerase chain reaction (PCR) application. The expressed enzyme was then purified by heat treatment followed by two steps of column chromatography after which optimum pH and temperature of the enzyme were evaluated to be 7.0 and 75 °C, respectively. The optimal buffer for PCR with Tpe DNA polymerase consisted of 50 mM Tris–HCl (pH 8.0), 2 mM MgCl₂, 80 mM KCl, and 0.02% Triton X-100. Tpe DNA polymerase revealed a 3.6-fold higher fidelity (3.37 × 10⁻⁶) than Taq DNA polymerase (12.13 × 10⁻⁶) and performed significantly more efficiently in PCR amplification than both Taq and Pfu DNA polymerases. Ratios of 31:1 of Taq to Tpe DNA polymerases allowed PCR amplification of targets up to 15 kb in length with a 2.2-fold higher fidelity than Taq DNA polymerase. The results of the PCR experiments indicate that Tpe DNA polymerase may provide a higher fidelity DNA amplification in a shorter reaction time.