FIG 4.

RPA is specifically required for rolling-circle RNA synthesis. The rolling-circle RNA template (1 picomole) was coated with RPA as shown schematically in panel A or gp32 as shown schematically in panel B. (C and D) The templates were tested for the ability to support RNA synthesis in the presence of NS5BΔ21 (open squares) or NS5BΔ21-NS3h (filled squares) for 60 min with increasing amounts of NS5B as described in Materials and Methods. Robust synthesis of RNA was observed only in the presence of RPA (C) and not in the presence of gp32 (D).