Fig. 1.
Schematic presentations (not to scale) of the genetically engineered SARS-CoV replicon encoding Renilla luciferase (A), of the domain organization of Nsp3 (B), and of constructs with deleted fragments (ΔX, SUD-ΔN, SUD-ΔM, SUD-ΔNM, and SUD-ΔC) within domains X–SUD of Nsp3 (C). Nsp – nonstructural protein 1–16, Mpro – main (or 3C-like, 3CL) protease, prim/pol – non-canonical polymerase activity (Xiao et al., 2012, te Velthuis et al., 2012), ssRBP – single-stranded RNA-binding protein, RdRp – RNA-dependent RNA polymerase, Hel – superfamily-1 helicase, ExoN/(7)N-GMtase – 3′-to-5′ exonuclease/7N-guanylmethyltransferase, NendoU – U-specific endoribonuclease, 2′O-Mtase – 2′O-methyltransferase, TRS-M – transcription-regulatory sequence of the M protein, RLuc – Renilla luciferase, N – nucleocapsid protein, pA – a synthetic poly(A) tail, Rz – hepatitis delta virus ribozyme, BGH – bovine growth hormone termination and polyadenylation sequence, UB1 – ubiquitin-like domain 1, Ac – acidic domain, X – X domain, SUD – SARS-unique domain, UB2 – ubiquitin-like domain 2 preceding the papain-like cysteine protease (PLpro), NAB – nucleic acid-binding domain, G2M – coronavirus group 2 marker, TM1 and TM2 – transmembrane regions, ZF – zinc-finger, Y – uncharacterized domain. As shown schematically in panel C, Δ indicates a deletion of the X domain or of domains N, M, C, NM, or the complete SUD-coding sequences.