Selective inhibition of herpes simplex virus type-1 uracil-DNA glycosylaseby designed substrate analogs

Cytosine deamination and the misincorporation of 2'-dUrd into DNA during re plication result in the presence of uracil in DNA. Uracil-DNA glycosylases (UDGs) initiate the excision repair of this aberrant base by catalyzing the hydrolysis of the N-glycosidic bond. UDGs are expressed by nearly all know n organisms, including some viruses, in which the functional role of the UD G protein remains unresolved. This issue could in principle be addressed by the availability of designed synthetic inhibitors that target the viral UD G without affecting the endogenous human UDG. Here, we report that double-s tranded and single-stranded oligonucleotides incorporating either of two dU rd analogs tightly bind and inhibit the activity of herpes simplex virus ty pe-1 (HSV-1) UDG. Both inhibitors are exquisitely specific for the Hm-l UDG over the human UDG. These inhibitors should prove useful in structural stu dies aimed at understanding substrate recognition and catalysis by UDGs, as well as in elucidating the biologic role of UDGs in the life cycle of herp esviruses.