Nucleotide sequence of the marmoset herpesvirus thymidine kinase gene and predicted amino acid sequence of thymidine kinase polypeptide.

The nucleotide sequence of a 2549-bp DNA fragment containing the entire coding region of the marmoset herpesvirus (MarHV) thymidine kinase gene (tk) and the flanking sequences was determined by the dideoxynucleotide chain termination method. The MarHV thymidine kinase polypeptide predicted from the nucleotide sequence contained 376 amino acids and had a molecular weight of 41,281. The sequencing data also reveal that the coding portion of another MarHV gene probably begins only 292 nucleotides downstream from the stop codon of the MarHV tk gene. There was relatively little nucleotide sequence homology between the MarHV tk gene and that of the herpes simplex virus (HSV) types 1 and 2 tk genes. Comparisons of the predicted amino acid sequences of the MarHV thymidine kinase polypeptide with that of the HSV-1 and HSV-2 thymidine kinase polypeptides, however, revealed clear, but interrupted, homology within several regions of the polypeptide chains. Amino acid sequence homology was particularly striking at residues 10 to 27 of the MarHV thymidine kinase polypeptide and residues 49 to 66 of the HSV-1 and HSV-2 thymidine kinase polypeptides. These same amino acid residues exhibit noticeable sequence homology to the mitochondrial beta subunit ATPase, oncogene p21 protein, adenylate kinase, and to other nucleotide-binding proteins. It has been proposed that the indicated regions of homology are elements of a nucleotide-binding pocket in ATPase, p21, and adenylate kinase, raising the possibility that amino acid residues 15 to 25 of the MarHV thymidine kinase and 54 to 64 of the HSV-1 and HSV-2 enzymes are likewise parts of nucleotide-binding sites.