Purification of SARS-CoV-2 Viral Proteins

Recombinant proteins were expressed and purified using the methods described previously (35 (link)). Briefly, His-tagged nsp1β and the PLP2 domain of nsp2 were expressed in Escherichia coli BL21(DE3)pLysS (Thermo Fisher Scientific, Waltham, MA) and purified using Ni-nitrilotriacetic acid agarose resin (Ni-NTA; Qiagen, Germantown, MD). GST-tagged nsp1β and mutants thereof were expressed in E. coli BL21(DE3)pLysS (Thermo Fisher Scientific, Waltham, MA) and purified using glutathione agarose resin (Thermo Fisher Scientific, Waltham, MA). His-tagged PCBP2 was expressed in E. coli BL21(DE3)pLysS (Thermo Fisher Scientific, Waltham, MA) and purified using Ni-NTA resin (Qiagen, Germantown, MD). Proteins were dialyzed, quantified with the Pierce bicinchoninic acid (BCA) protein assay kit (Thermo Fisher Scientific, Waltham, MA), and stored at −80°C.