The ribonucleotide reductase induced by herpes simplex virus type 1 involves minimally a complex of two polypeptides (136K and 38K)

Herpes simplex virus type 1 (HSV-1) encodes a polypeptide of apparent mol. wt. 136 000 (Vmw136) known to be a component of the virus-specified ribonucleotide reductase. Monoclonal antibodies that precipitate this polypeptide also precipitate a polypeptide of mol. wt. 38 000 (Vmw38) from extracts of HSV-1-infected cells. The basis for this co-precipitation has been investigated using a monoclonal antibody directed against Vmw136 and an oligopeptide-induced antiserum directed against the carboxy terminus of Vmw38. We have also made use of a temperature-sensitive (ts) mutant of HSV-1 which maps within the sequences encoding Vmw136 and which induces a thermolabile ribonucleotide reductase. Our experiments show (i) Vmw136 and Vmw38 form a complex in infected cells and (ii) the mutation in the ts mutant results in the two polypeptides being unable to form the complex at the non-permissive temperature. We speculate that association of the two polypeptides is necessary for ribonucleotide reductase activity. No evidence was found for involvement of host proteins in the proposed virus-induced ribonucleotide reductase complex. The terms RR1 and RR2 are suggested for the large and small subunits of the HSV-induced enzyme.