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

Cytosine deamination and the misincorporation of 2'-dUrd into DNA during replication 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 known organisms, including some viruses, in which the functional role of the UDG protein remains unresolved. This issue could in principle be addressed by the availability of designed synthetic inhibitors that target the viral UDG without affecting the endogenous human UDG. Here, we report that double-stranded and single-stranded oligonucleotides incorporating either of two dUrd analogs tightly bind and inhibit the activity of herpes simplex virus type-1 (HSV-1) UDG. Both inhibitors are exquisitely specific for the HSV-1 UDG over the human UDG. These inhibitors should prove useful in structural studies aimed at understanding substrate recognition and catalysis by UDGs, as well as in elucidating the biologic role of UDGs in the life cycle of herpesviruses.