Identification of a herpes simplex virus type 1 polypeptide which is a component of the virus-induced ribonucleotide reductase.

We have characterized a temperature-sensitive mutant of herpes simplex virus type 1 (HSV-1), 17tsVP1207, that induces a thermolabile ribonucleotide reductase activity. This mutant was derived from the multiple mutant tsG. Fine-structure mapping studies showed that the defect in 17tsVP1207 lies within an 800 bp sequence between genome map coordinates 0.580 and 0.585 in the gene encoding a polypeptide of 140 000 mol. wt. (Vmw136, ICP6). Since the mutation in this polypeptide produced a temperature-sensitive ribonucleotide reductase activity, Vmw136 must be a component of the herpes simplex virus-induced ribonucleotide reductase. The mRNA of Vmw136 has a common 3' terminus with an mRNA encoding a 38 000 mol. wt. polypeptide (Vmw38). Although the polypeptide-coding sequences of these mRNAs do not overlap, monoclonal antibodies against Vmw136 immunoprecipitated Vmw38 as well as Vmw136 from wild-type HSV-1-infected cells. Our data do not exclude the possibility that Vmw38 is part of the ribonucleotide reductase complex but suggest that this species on its own is not responsible for the HSV-induced enzyme activity.