Two early vaccinia virus genes encode polypeptides related to protein kinases

Vaccinia virus particles contain a protein kinase with an Mr of 62K calculated from sedimentation rate. We have sequenced the SalI G restriction fragment of the vaccinia virus genome near to the right inverted terminal repeat and have identified two genes which share 36% amino acid identity with each other and are related to the family of protein kinase genes. One gene, designated B1R, encodes a 34.2K protein which shares 27% identity with a protein kinase encoded by the herpes simplex virus type 1 US3 gene and contains conserved motifs characteristic of protein kinases of serine/threonine specificity. The second gene, B12R, encodes a protein of 33.3K which is poorly related to known protein kinases and lacks specific amino acids at several highly conserved key positions. The deduced partial amino acid sequence of a gene in the corresponding region of the cowpox virus genome is identical to B12R except for one conservative amino acid substitution. Both of the vaccinia virus genes are transcribed towards the right-hand end of the genome early during infection. It is possible that the product of either or both of these genes associates to form a homo- or heterodimer that represents the 62K virion-associated protein kinase.