L-thymidine is phosphorylated by herpes simplex virus type 1 thymidine kinase and inhibits viral growth.
We have demonstrated that herpes simplex 1 (HSV1) thymidine kinase (TK) shows no stereospecificity for D- and L-beta-nucleosides. In vitro, L enantiomers are not recognized by human TK, but function as specific substrates for the viral enzyme in the order: L-thymidine (L-T) >> 2'-deoxy-L-guanosine (L-dG) > 2'-deoxy-L-uridine (L-dU) > 2'-deoxy-L-cytidine (L-dC) > 2'-deoxy- L-adenosine (L-dA). HSV1 TK phosphorylates both thymidine enantiomers to their corresponding monophosphates with identical efficiency and the Ki of L-T (2 microM) is almost identical to the Km for the natural substrate D-T (2.8 microM). The L enantiomer reduces the incorporation of exogenous [3H]T into cellular DNA in HeLa TK-/HSV1 TK+ but not in wild-type HeLa cells, without affecting RNA, protein synthesis, cell growth, and viability. L-T markedly reduces HSV1 multiplication in HeLa cells. Our observations could lead to the development of a novel class of antiviral drugs characterized by low toxicity.
Spadari
S
S
Istituto di Genetica Biochimica ed Evoluzionistica, CNR, Pavia, Italy.
Maga
G
G
Focher
F
F
Ciarrocchi
G
G
Manservigi
R
R
Arcamone
F
F
Capobianco
M
M
Carcuro
A
A
Colonna
F
F
Iotti
S
S
D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003853:Deoxyribonucleosides / Q000138:chemical synthesis* / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007930:Leucine / Q000378:metabolism; D018139:Simplexvirus / Q000187:drug effects* / Q000201:enzymology; D013237:Stereoisomerism; D013936:Thymidine / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology*; D013937:Thymidine Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014529:Uridine / Q000378:metabolism
D003853:Deoxyribonucleosides; D013937:Thymidine Kinase; D007930:Leucine; D013936:Thymidine; D014529:Uridine