Herpes simplex virus specifies two subunits of ribonucleotide reductase encoded by 3'-coterminal transcripts

We have previously described a transcription unit located between map coordinates 0.558 and 0.595 on the herpes simplex virus type 2 strain 333 genome which encodes two mRNAs of 5.0 and 1.2 kilobases that share a common 3' terminus, and we have determined the nucleotide sequence of a 38,000-dalton protein specified by the smaller RNA (D. A. Galloway and M. A. Swain, J. Virol. 49:724-730, 1984). The entire nucleotide sequence of the 140,000-dalton protein specified by a 3,432-base-pair open reading frame within the large mRNA is presented, as are transcriptional regulatory sequences upstream of the RNA. The 140,000-dalton protein shows strong homology with the large subunit of well-characterized ribonucleotide reductase enzymes from the mouse and from Escherichia coli and with an Epstein-Barr virus gene. The 38,000-dalton protein has been shown previously to have homology with the small subunit of these enzymes (B.-M. Sjoberg, H. Eklund, J. A. Fuchs, J. Carlson, N. M. Standart, J. V. Ruderman, S. J. Bray, and T. Hunt, FEBS Lett. 183:99-102, 1985). This is the first example of a herpesvirus transcriptional unit that encodes functionally related proteins.