DNA Polymerase β and DNA Synthesis in Xenopus Oocytes and in a Nuclear Extract

The identities of the DNA polymerases required for conversion of single-strand (ss) M13 DNA to double-strand (ds) M13 DNA were examined both in injected Xenopus laevis oocytes and in an oocyte nuclear extract. Inhibitors and antibodies specific to DNA polymerases α and β were used. In nuclear extracts, inhibition by the antibody to polymerase β could be reversed by purified polymerase β. The polymerase β inhibitors, dideoxythymidine triphosphate (ddTTP) and dideoxycytidine triphosphate (ddCTP), also blocked DNA synthesis and indicated that polymerase β is involved in the conversion of ssDNA to dsDNA. These results also may have particular significance for emerging evidence of an ssDNA replication mode in eukaryotic cells.