|Bacteria Escherichia coli
|McDonald WF, Traktman P. Vaccinia virus DNA polymerase. In vitro analysis of parameters affecting processivity. J Biol Chem. 1994 Dec 9 269(49):31190-7. abstract, p.31193 right column top paragraph & p.31196 left column 2nd paragraphPubMed ID7983061
|Abstract: "The polymerization and proofreading activities of the vaccinia virus DNA polymerase reside within a 116-kDa catalytic polypeptide. [Investigators] report here an investigation of the intrinsic processivity of this enzyme on both natural and homopolymeric DNA templates. Inclusion of the Escherichia coli helix destabilizing protein allowed the viral enzyme, which lacks strand displacement activity, to utilize a singly primed M13 DNA template."
|Abstract: "The apparent rate of primer elongation varied with the enzyme/template ratio and reached a maximum of 8 nt/s." P.31193 left column bottom paragraph: "Under these conditions, primer elongation by the vaccinia enzyme occurred at an average rate of 8 nt/s." P.31196 left column 2nd paragraph: "In [investigators'] analysis of enzyme processivity, [they] found that primer elongation on both natural and homopolymeric DNA templates was achieved in a distributive or nonprocessive manner under reaction conditions that were optimal for DNA synthesis on gapped DNA (ref 9). Conversion of singly primed M13 DNA to the duplex RFII [Replicative Form II] product required the presence of a helix destabilizing protein (E. coli SSB (single-stranded binding protein)). RFII formation was completed at a
synthetic rate that varied with enzyme concentration: higher polymerase concentrations resulted in faster apparent rates of primer elongation. A maximal rate of dNTP incorporation of 8
nt/s at 30˚C was detected when enzyme concentrations were in vast excess over the primed DNA template. A clue to the relative slowness of this elongation rate was provided by template challenge experiments, which indicated that perhaps only one or two nucleotides were incorporated during a single cycle of enzyme-template binding."