Enzymatic degradation of uracil containing DNA. II. Evidence for N glycosidase and nuclease activities in unfractionated extracts of Bacillus subtilis

Further studies have confirmed earlier observation that in the presence of EDTA, degradation of phage BPS2 [³H] uracil labeled DNA is effected by an N glycosidase activity in extracts of Bacillus subtilis that removes free uracil from DNA. In addition, such extracts contain a nuclease activity that attacks PBS2 DNA in the presence of CaCl₂. The nuclease activity is not observed under conditions that inactivate N glycosidase activity but does attack DNA that has been preincubated to remove uracil by N glycosidase action. The authors therefore postulate that the nuclease requires N glycosidase action to generate substrate for its activity, i.e., the nuclease appears to attack depyrimidinated sites rather than uracil sites in phage PBS2 DNA.