FIG. 3.

De novo initiation and primer extension by the three recombinant viral RdRps in the presence of Mg²⁺ or Mn²⁺. (A) Titration of the effects of increasing Mg²⁺ on RNA synthesis by the HCV RdRp. All RdRp products were normalized to the primer extension (PE) RNA in the reaction mixture with 2 mM Mg²⁺. (B) Titration of the effects of increasing Mn²⁺ by the HCV RdRp. All RdRp products were normalized to the primer extension (PE) reaction mixture with 2 mM Mn²⁺. (C) RNA synthesis by the three RdRps (80 nM each). De novo initiation products from LE19 and LE21 are 19 and 21 nt long, respectively, while the primer extension products are 32 or 34 nt long. The ratios of the de novo initiation to the primer extension (PE) products within each reaction are shown below the autoradiogram. −, reaction performed without exogenously provided metal ions.