The 1.75-Angstrom crystal structure of the uracil-DNA glycosylase from
herpes simplex virus type-L reveals a new fold, distantly related to
dinucleotide-binding proteins. Complexes with a trideoxynucleotide, an
d with uracil, define the DNA-binding site and allow a detailed unders
tanding of the exquisitely specific recognition of uracil in DNA. The
overall structure suggests binding models for elongated single- and do
uble-stranded DNA substrates. Conserved residues close to the uracil-b
inding site suggest a catalytic mechanism for hydrolytic base excision
.