Analysis of the non-sense mutants of varicella-zoster virus thymidine kinase.
Three non-sense mutants of varicella-zoster virus (VZV) thymidine kinase (TK) gene, VZTK325, VZTK278 and VZTK224, were isolated. The mutants had a single nucleotide substitution at codons 326, 279 and 225, which changed the codon of TGG (tryptophan) to the stop codon TGA. The wild type (WT) and mutant TKs were expressed in E. coli cells and their characteristics were evaluated. VZTK224 lost TK activity, but VZTK325 and VZTK278 maintained 74.8% and 21.2% of the WT TK activity. On the other hand, all mutants lost the thymidylate kinase activity. Moreover, VZTK325 and VZTK278 polypeptides were heat-labile. These data suggest that the carboxy-terminal portion of herpesvirus TK plays an important role in the stable folding of TK and thymidylate kinase activity.
Suzutani
T
T
Department of Microbiology, Asahikawa Medical College, Japan.
Koyano
S
S
Saijo
M
M
Chiba
A
A
Azuma
M
M
D006361:Heating; D014645:Herpesvirus 3, Human / Q000201:enzymology* / Q000235:genetics; D009154:Mutation; D017384:Sequence Deletion; D013937:Thymidine Kinase / Q000235:genetics* / Q000378:metabolism
D013937:Thymidine Kinase