FIG 3.

Influence of P/T complexes on the efficiency of the primer extension reaction catalyzed by SARS-CoV-2 RdRp. (A) RNA primers (primers I, II, and III) and RNA template used in the experiments whose results are shown in panel B. (B) Primer extension assay using the different P/T complexes from panel A. Four nsp12 concentrations (6.25 nM, 12.5 nM, 25 nM, 50 nM; indicated above the gel), 2 μM nsp8-7 (2 μM nsp8 and 10 μM nsp7), and 5 nM concentrations of different P/T complexes (formed by annealing primer I, II, or III with the template shown in panel A) were used in the assay. The reactions were initiated by the addition of 100 μM rNTP and continued at 37°C for 1 h, and the products were separated on denaturing polyacrylamide gels. Three P/T complexes without nsp12 added were used as negative controls (left three lanes).