Figure 4.

Inhibition of RNA synthesis by 3′-dGTP using a poly(rC) template. (A) Effect of increasing concentrations of 3′-dGTP on the initiation and full-length RNA product formation. The nucleoside analog was added to reaction mixtures containing 1 μM poly(rC), 10 μM [α³²-P] GTP and 1 μM nsp8. Lanes 1–5 show the products of the reactions performed using the following concentrations of 3′-dGTP: 0, 100, 500 nM, 1 and 10 μM. Reactions were allowed to proceed for 60 min. M, RNA marker synthesized using T7 RNA polymerase and an appropriate template. (B) Same as in (A) using 10 μM oligo(rC₁₅) as a template in conjunction with 1 μM HCV NS5B. Each chain terminated band product is indicated on the right by an asterisk (^*). For each 3′-dGTP concentration (lanes 1–5: 0, 5, 10, 50 and 100 μM, respectively), the reaction was allowed to proceed for 30, 60 and 120 min.