Abstract
During eukaryotic DNA synthesis there is formation of, in addition to Okazaki fragments, discrete 10-kilobase (kb) DNA replication intermediates. The ligation of 10-kb DNA replication intermediates to high MW DNA was investigated using the drug 3-aminobenzamide, an inhibitor of poly(ADP-ribose) synthetase. In human melanoma cells treated with this inhibitor, there is an accumulation of 10-kb DNA. In cells treated with aphidicolin, which inhibits DNA polymerase .alpha., there is continued ligation of 10-kb DNA to high MW DNA. Using sequential treatment with aphidicolin and 3-aminobenzamide, the conversion of radiolabeled Okazaki fragments into 10-kb intermediates can be observed. The 10-kb DNA pieces are not ligated to high MW DNA in the presence of 3-aminobenzamide. Apparently, functioning poly(ADP-ribose) synthetase is necessary for the ligation process.