Escherichia coli double-strand uracil-DNA glycosylase (Dug) was purified to apparent homogeneity from bacteria that were defective in uracil-DNA glycosylase (Ung). After cloning the dug gene, recombinant Dug was overexpressed, purified, and characterized with respect to activity, substrate specificity, product DNA binding, and mechanism of action. Purified Dug excised both uracil...