The mechanism of phosphorylation of anti-HIV D4T by nucleoside diphosphate kinase.
The last step in the intracellular activation of antiviral nucleoside analogs is the addition of the third phosphate by nucleoside diphosphate (NDP) kinase resulting in the synthesis of the viral reverse transcriptase substrates. We have previously shown that dideoxynucleotide analogs and 3'-deoxy-3'-azidothymidine (AZT) as di- or triphosphate are poor substrates for NDP kinase. By use of protein fluorescence, we monitor the phosphotransfer between the enzyme and the nucleotide analog. Here, we have studied the reactivity of D4T (2',3'-dideoxy-2',3'-didehydrothymidine; stavudine) as di- (DP) or triphosphate (TP) at the pre-steady state. The catalytic efficiency of D4T-DP or -TP is increased by a factor of 10 compared with AZT-DP or -TP, respectively. We use an inactive mutant of NDP kinase to monitor the binding of a TP derivative, and show that the affinity for D4T-TP is in the same range as for the natural substrate deoxythymidine triphosphate, but is 30 times higher than for AZT-TP. Our results indicate that D4T should be efficiently phosphorylated after intracellular maturation of a prodrug into D4T-monophosphate.
Schneider
B
B
Unité de Régulation Enzymatique des Activités Cellulaires, Centre National de la Recherche Scientifique, Unité de Recherche Associée 1773, 558, Institut Pasteur, Paris, France.
Biondi
R
R
Sarfati
R
R
Agou
F
F
Guerreiro
C
C
Deville-Bonne
D
D
Veron
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D019380:Anti-HIV Agents / Q000378:metabolism*; D054306:Dideoxynucleotides; D054303:HIV Reverse Transcriptase / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D009701:Nucleoside-Diphosphate Kinase / Q000378:metabolism*; D010766:Phosphorylation; D018119:Stavudine / Q000378:metabolism*; D013942:Thymine Nucleotides / Q000378:metabolism; D015215:Zidovudine / Q000031:analogs & derivatives / Q000378:metabolism
D019380:Anti-HIV Agents; D054306:Dideoxynucleotides; D013942:Thymine Nucleotides; C064181:3'-azido-3'-deoxythymidine 5'-diphosphate; D015215:Zidovudine; D000255:Adenosine Triphosphate; D018119:Stavudine; D009701:Nucleoside-Diphosphate Kinase; D054303:HIV Reverse Transcriptase; C024157:thymidine 5'-triphosphate