title: Evolution of the herpes thymidine kinase: identification and comparison of the equine herpesvirus 1 thymidine kinase gene reveals similarity to a cell-encoded thymidylate kinase.
abstract: We have identified the equine herpesvirus 1 (EHV-1) thymidine kinase gene (TK) by DNA-mediated transformation and by DNA sequencing. Alignment of the amino acid sequence of the EHV-1 TK with the TKs from 3 other herpesviruses revealed regions of homology, some of which correspond to the previously identified substrate binding sites, while others have as yet, no assigned function. In particular, the strict conservation of an aspartate within the proposed nucleoside binding site suggests a role in ATP binding for this residue. Comparison of 5 herpes TKs with the thymidylate kinase of yeast revealed significant similarity which was strongest in those regions important to catalytic activity of the herpes TKs, and, therefore we propose that the herpes TK may be derived from a cellular thymidylate kinase. The implications for the evolution of enzyme activities within a pathway of nucleotide metabolism are discussed.
authors.affiliation: School of Biological Sciences, Macquarie University, Sydney, NSW, Australia.
authors.forename: G R
authors.initials: GR
authors.lastname: Robertson
authors.forename: J M
authors.initials: JM
authors.lastname: Whalley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002461:Cell Line, Transformed; D005796:Genes; D006564:Herpesviridae / Q000201:enzymology*; D004861:Herpesvirus 1, Equid / Q000201:enzymology* / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009703:Nucleoside-Phosphate Kinase / Q000235:genetics*; D010770:Phosphotransferases / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D012689:Sequence Homology, Nucleic Acid; D013937:Thymidine Kinase / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D010770:Phosphotransferases; D013937:Thymidine Kinase; D009703:Nucleoside-Phosphate Kinase; C020093:dTMP kinase