The substrate activity of (S)-9-[3-hydroxy-(2-phosphonomethoxy)propyl]adenine diphosphate toward DNA polymerases alpha, delta and epsilon.

In this study, we examined the substrate potency of (S)-9-[3-hydroxy-(2-phosphonomethoxy)propyl]- adenine diphosphate (HPMPApp) toward DNA polymerases alpha, delta and epsilon. The efficiency of HPMPApp incorporation decreased in the order pol epsilon >pol delta =pol alpha and was from 5.4- to 23-fold lower than that of dATP. Depending on which template-primer was used, the HPMPAppKm value was 3.3- and 8.3- (pol alpha), 3- and 0.82- (pol delta) or 2-fold (pol epsilon) higher than dATPKm. The ability of HPMPA to accumulate in DNA decreased in the order pol epsilon >pol alpha >pol delta. The difference between the elongation rate of DNA with and without one HPMPA molecule at 3' termini was about 1.1-2.3 fold. The 3'-5'-exonuclease activity of pol delta and epsilon can excise HPMPA from DNA. These observations indicate that interaction of HPMPApp with pol alpha, delta and epsilon may contribute to its cellular toxicity and explain its antiviral activity against polyomavirus.