Characterization and PCR application of a new high-fidelity DNA polymerase from Thermococcus waiotapuensis

The family B DNA polymerase gene from the euryarchaeon Thermococcus waiotapuensis (Twa) contains an open reading frame of 4404 bases that encodes 1467 amino acid residues. The gene is split by two intein-coding sequences that forms a continuous open reading frame with the three polymerase exteins. Twa DNA polymerase genes with (whole gene) and without (genetically intein-spliced) inteins were expressed in Escherichia coli Rosetta(DE3)pLysS. The inteins of the expressed whole gene were easily spliced during purification. The molecular mass of the purified Two DNA polymerase was about 90 kDa, as estimated by SDS-PAGE. The optimal pH for Twa DNA polymerase activity was 6.0 and the optimal temperature was 75 degrees C. The enzyme was activated by magnesium ions. The half-life of the enzyme at 99 degrees C was about 4 h. The optimal buffer for PCR with Two DNA polymerase was 50 mM Tris-HCl (pH 8.2), 2.0 mM MgCl2, 30 mM KCl, 2.0 mM (NH4)(2)SO4, 0.01% Triton X-100, and 0.005% BSA. The PCR fidelity of Twa DNA polymerase was higher than Pfu, KOD and Vent DNA polymerases. A ratio of 15:1 Taq:Twa DNA polymerase efficiently facilitated long-range PCR. (C) 2012 Elsevier Inc. All rights reserved.