Yeast DNA Polymerases: Antigenic Relationship, Use of RNA Primer and Associated Exonuclease Activity

Abstract

Highly purified preparations of DNA polymerases A and B from yeast [Saccharomyces cerevisiae] were compared with respect to antigenic relationship, ability to use ribonucleotide primers and associated nuclease activity. Antiserum [rabbit] directed against DNA polymerase A inhibits this enzyme but does not interfere with the activity of DNA polymerase B or of mitochondrial DNA polymerase, nor does it precipitate the latter 2 enzymes. DNA polymerase A is capable of using oligo(ribouridylic acid) as a primer for the polymerization of dTMP. This reaction is not catalyzed by polymerase B to any significant extent. Whereas DNA polymerase A is devoid of nuclease activity, DNA polymerase B catalyses an exonucleolytic release of mononucleotide units from the 3'' end of polynucleotides. The results of several experiments suggest that this nuclease activity is associated with the DNA polymerase B molecule.