Identification and mapping of two polypeptides encoded within the herpes simplex virus type 1 thymidine kinase gene...

mRNA's homologous to the herpes simplex virus type 1 DNA restriction endonuclease fragment BamHI p, which contains the thymidine kinase gene, have been identified and mapped by hybrid-arrested translation and mRNA selection. Such mRNA's, when translated in vitro, directed the synthesis of polypeptides of apparent molecular weights 43,000 (VI43) and 39,000 (VI39). mRNA for enzymatically active thymidine kinase was enriched by more than 20-fold after selection. Mapping was carried out with restriction endonuclease fragments of BamHI p, and locations of the 5' and 3' termini of VI43 mRNA were deduced. Analysis of nucleotide sequences around the 5' terminus revealed several consensus sequences commonly found at the start of eucaryotic mRNA's and which are presumably involved in initiation of transcription by RNA polymerase II. Translation of mRNA's for VI43, VI39, and the thymidine kinase enzyme was arrested only by a 1,170-base-pair region of BamHI p. Since this region is insufficient for adjacent genes, coding sequences for VI43 and VI39 must overlap; the possible relationship of these two polypeptides is discussed. A virus-induced product equivalent to VI39 was detected in infected cells.