Excises uracil residues from the DNA which can arise as a result of misincorporation of dUMP residues by DNA polymerase or due to deamination of cytosine. Hydrolyzes single-stranded DNA or mismatched double-stranded DNA and polynucleotides, releasing free uracil. Belongs to the uracil-DNA glycosylase (UDG) superfamily. UNG family. Was originally thought to originate from Pseudomonas denitrificans, but similarity searches show that the sequence is much closer to Sinorhizobium. The entry's taxonomy has been changed.