Endonuclease for apurinic sites in yeast. Comparison of the enzyme activity in the wild type and in rad mutants of Saccharomyces cerevisiae to MNS.

It was found that yeast cells contain an endonuclease specific for apurinic sites in DNA which has no effect on DNA with normal strands or on strands with alkylated sites. The enzyme activity was studied in the RAD strain and in rad 6, rad 18-2 and rad 21 mutants, all very sensitive to MMS, as compared to the wild type. The level of endonuclease activity does not differ much between the tested strains, regardless of their differences in susceptibility to MMS. The enzyme activity is not induced by pretreatment of the cells with this mutagen.