THE STRUCTURAL BASIS OF SPECIFIC BASE-EXCISION REPAIR BY URACIL-DNA GLYCOSYLASE

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 .