Mammalian cyclin/PCNA (DNA polymerase delta auxiliary protein) stimulates processive DNA synthesis by yeast DNA polymerase III.
Human cyclin/PCNA (proliferating cell nuclear antigen) is structurally, functionally, and immunologically homologous to the calf thymus auxiliary protein for DNA polymerase delta. This auxiliary protein has been investigated as a stimulatory factor for the nuclear DNA polymerases from S. cerevisiae. Calf cyclin/PCNA enhances by more than ten-fold the ability of DNA polymerase III to replicate templates with high template/primer ratios, e.g. poly(dA).oligo(dT) (40:1). The degree of stimulation increases with the template/primer ratio. At a high template/primer ratio, i.e. low primer density, cyclin/PCNA greatly increases processive DNA synthesis by DNA polymerase III. At low template/primer ratios (e.g. poly(dA).oligo(dT) (2.5:1), where addition of cyclin/PCNA only minimally increases the processivity of DNA polymerase III, a several-fold stimulation of total DNA synthesis is still observed. This indicates that cyclin/PCNA may also increase productive binding of DNA polymerase III to the template-primer and stabilize the template-primer-polymerase complex. The activity of yeast DNA polymerases I and II is not affected by addition of cyclin/PCNA. These results strengthen the hypothesis that yeast DNA polymerase III is functionally analogous to the mammalian DNA polymerase delta.
D000818:Animals; D002417:Cattle; D004258:DNA Polymerase III / Q000378:metabolism*; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008274:Magnesium / Q000502:physiology; D009687:Nuclear Proteins / Q000502:physiology*; D018809:Proliferating Cell Nuclear Antigen; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013379:Substrate Specificity; D013698:Templates, Genetic
D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D008274:Magnesium