Identification of the Herpes Simplex Virus Protein Kinase as the Product of Viral Gene US3

1 MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR and 2 Department of Biochemistry, University of Glasgow, Glasgow G12 8QQ, U.K. Previous work has shown that a novel protein kinase is induced after infection of cultured cells with herpes simplex virus type 1 (HSV-1). Separately, it has been reported that the protein encoded by HSV-1 gene US3 shows similarity in its amino acid sequence to members of the protein kinase family of eukaryotes. We have investigated the possibility that these two observations are connected by preparing an antiserum to a synthetic oligopeptide corresponding to the carboxy-terminal eight amino acids of the US3 protein. This antiserum reacted on immunoblots with a polypeptide of apparent molecular weight 68000 from extracts of cells which had been infected with HSV-1. The antiserum also reacted strongly with a 68000 molecular weight species from a preparation of the novel HSV-1 protein kinase which had been extensively purified and resolved from other protein kinases. In addition, the purified preparation phosphory-lated a protein species, also of 68000 apparent molecular weight, when incubated with [ - 32 P]ATP. These data are consistent with gene US3 encoding the novel protein kinase induced after infection of cells with HSV-1. Keywords: HSV-1, protein kinase, oligopeptide-induced antiserum Received 27 April 1987; accepted 30 June 1987.