ROLE OF DNA POLYMERASE-ALPHA, POLYMERASE-BETA AND POLYMERASE-GAMMA IN NUCLEAR-DNA SYNTHESIS

The effects of the inhibitors 2′3′ dideoxythymidine triphosphate (ddTTP) and 1-β-d-arabinofuranosyl cytosine triphosphate (araCTP) on DNA synthesis in isolated S-phase HeLa S3 nuclei have been examined. These effects are compared with the effects of the same inhibitors in partially purified preparations of DNA polymerases α and β. The effect of ddTTP on partially purified DNA polymerase γ was also tested. DNA polymerases β and γ were very sensitive to ddTTP whereas DNA polymerase α and DNA synthesis in isolated nuclei were quite resistant. The synthesis and subsequent ligation of primary DNA pieces ('Okazaki fragments') were not affected by the presence of this inhibitor. DNA synthesis in isolated nuclei and DNA polymerase α activity were very sensitive to araCTP whereas DNA polymerase β was almost totally resistant to the inhibitor. The results indicate a major role for DNA polymerase α in DNA replication. © 1979.