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. Inhibited by UGI, a B.subtilis bacteriophage PBS2 peptide inhibitor. Optimum temperature is 26 degrees Celsius. Severe loss of unracil exision activity. Increased number of germ-cell corpses in response DNA damage induced by ionizing radiation. Belongs to the uracil-DNA glycosylase (UDG) superfamily. UNG family.