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Mammalian cyclin/PCNA (DNA polymerase δ auxiliary protein) stimulates processive DNA synthesis by yeast DNA polymerase III

1988; Oxford University Press; Volume: 16; Issue: 14 Linguagem: Inglês

10.1093/nar/16.14.6297

1362-4962

Peter Burgers,

Carcinogens and Genotoxicity Assessment

Human cyclin/PCNA (proliferating cell nuclear antigen) is structurally, functionally, and immunologically homologous to the calf thymus auxiliary protein for DNA polymerase δ. 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 δ.