Lack of stereospecificity of suid pseudorabies virus thymidine kinase.
We have partially purified suid pseudorabies virus (PRV) thymidine kinase from infected thymidine kinase- mouse cells, and cytosolic swine thymidine kinase from lymphatic glands, and we have found that PRV thymidine kinase, unlike the host enzyme, shows no stereospecificity for D- and L-beta-nucleosides. In vitro, unnatural L-enantiomers, except L-deoxycytidine, function as specific inhibitors for the viral enzyme in the order: L-thymidine >> L-deoxyguanosine > L-deoxyuridine > L-deoxyadenosine. Contrary to human and swine thymidine kinases and like herpes simplex virus-1 and -2 thymidine kinases, PRV thymidine kinase phosphorylates both the natural (D-) and the unnatural (L-) thymidine enantiomers to their corresponding monophosphates with comparable efficiency. The kinetic parameters Vmax/Km for D- and L-thymidine are 3.7 and 2.3 respectively. Our results demonstrate that the lack of stereospecificity might be a common feature of the thymidine kinases that are encoded by human and animal herpes viruses. These observations could lead to the development of a novel class of antiviral drugs.
Istituto de Genetica Biochimica ed Evoluzionistica, CNR, Pavia, Italy.
G
G
Maga
A
A
Verri
L
L
Bonizzi
W
W
Ponti
G
G
Poli
A
A
Garbesi
D
D
Niccolai
S
S
Spadari
F
F
Focher
D001667:Binding, Competitive; D003839:Deoxyadenosines / Q000494:pharmacology; D003849:Deoxyguanosine / Q000494:pharmacology; D003857:Deoxyuridine / Q000494:pharmacology; D011558:Herpesvirus 1, Suid / Q000201:enzymology*; D009705:Nucleosides / Q000737:chemistry* / Q000378:metabolism*; D010766:Phosphorylation; D013237:Stereoisomerism; D013379:Substrate Specificity; D013936:Thymidine / Q000378:metabolism / Q000494:pharmacology; D013937:Thymidine Kinase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*
D003839:Deoxyadenosines; D009705:Nucleosides; D013937:Thymidine Kinase; D003849:Deoxyguanosine; D013936:Thymidine; D003857:Deoxyuridine