Chiral Discrimination of Enantiomeric 2′-Deoxythymidine 5′-Triphosphate by HIV-1 Reverse Transcriptase and Eukaryotic DNA Polymerases

Inhibitory effects of 2′-deoxy-L-thymidine 5′-triphosphate (L-dTTP), the enantiomer of the natural substrate D-dTTP, on the activity of mammalian DNA polymerases α, β and γ, Escherichia coli DNA polymerase I and human immunodeficiency virus 1 (HIV-1) reverse transcriptase were examined. When poly(rA) n-oligo(dT) 12-18 was used as the template-primer, L-dTTP showed remarkable inhibitory effect on HIV-1 reverse transcriptase in competitive fashion with respect to the substrate dTTP. In contrast, L-dTTP did not inhibit DNA polymerases α and was slightly inhibitory to DNA polymerase β. These results suggest that the nuclear DNA polymerases α and β showed high specificity for the substrate with the natural configuration of the sugar moiety, D-dTTP, exhibiting little or no ability to recognize L-dTTP, whereas HIV-1 reverse transcriptase essentially lacked the ability to differentiate the D- and L-sugar moieties.