Characterization of a DNA polymerase from the hyperthermophile archaea Thermococcus litoralis. Vent DNA polymerase, steady state kinetics, thermal stability, processivity, strand displacement, and exonuclease activities.
We have isolated, cloned, and characterized a DNA polymerase from the hyperthermophile archaea Thermococcus litoralis, the Tli DNA polymerase (also referred to as Vent DNA polymerase). The enzyme is extremely thermostable, having a half-life of 8 h at 95 degrees C and about 2 h at 100 degrees C. Pseudo-first-order kinetics at 70 degrees C reveal an extremely low Km for a primed M13mp18 substrate (0.1 nM), coupled with a relatively high Km for dNTPs (50 microM). Accompanying extension rates are on the order of 1000 nucleotides/min. Synthesis by the polymerase is largely distributive, adding an average of 7 nucleotides/initiation event. This distributive synthesis can generate products of at least 10,000 bases. Tli DNA polymerase contains a 3'-->5' exonuclease activity that enhances the fidelity of replication by the enzyme (Mattila, P., Korpela, J., Tenkanen, T. and Pitkanen, K. (1991) Nucleic Acids Res. 19, 4967-4973). A 2-amino acid substitution within the conserved exonuclease domain abolishes both double and single strand-dependent exonuclease activity, without altering kinetic parameters for polymerization on a primed single-stranded template. Strand displacement activity by the mutated and unmutated forms increases with increasing temperature and is enhanced in the exonuclease-deficient form of the enzyme.
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New England Biolabs, Inc., Beverly, Massachusetts 01915.
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D001105:Archaea / Q000201:enzymology*; D001483:Base Sequence; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D006358:Hot Temperature; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism
D011994:Recombinant Proteins; C070331:Tli polymerase; D004259:DNA-Directed DNA Polymerase