FIG 4.

Purification and RNA synthesis activity of SARS-CoV-2 nsp7/8/12 complex. (A) SARS-CoV-2 nsp7, nsp8 and nsp12 were expressed and purified from E. coli (nsp7 and nsp8) or Sf9 (nsp12) cells and visualised by SDS PAGE. (B) Schematic of 40 nt RNA template and 20 nt radiolabelled primer. (C) Purified nsp7/8/12 complex was tested for in vitro activity in the presence or absence of NTPs and RNA template. The 20 nt primer and 40 nt product ran slightly slower than the markers, possibly due to differences in the RNA sequence or phosphorylation state. Quantification of the transcription products is shown on the right. Quantification is from n=3 independently prepared reactions using the same nsp7/8/12 protein preparation, error bars represent standard deviation.