p53 protein exhibits 3'-to-5' exonuclease activity

The p53 protein shows exonuclease activity and degrades DNA with a 3'-to-5' polarity in the presence of Mg2+. The exonuclease activity is specific for the purified wild-type protein as p53 mutants lack the activity. The activity copurifies with p53 during the preparation of the wild-type protein but fails to copurify with mutant p53. The enzyme activity can be reconstituted from urea-denatured and SDS gel-purified p53 and mapped to the core region of the p53 molecule.