Fig. 1

Design of recombinant PEDVs with mutations at different active sites of nsp14-ExoN. a Alignment of nsp14-ExoN amino acid sequences from selected coronaviruses. Sequences of the ExoN domains in PEDV (KY499262), IBV (NP_040829), MHV (NP_045298), MERS-CoV (NC-019843), SARS-CoV (NC_004718), and SARS-CoV-2 (NC_045512.2) were used for the analysis. b Alignment of partial nsp14 amino acid sequences of the infectious clone derived PC22A (icPC22A) and the eight PEDV nsp14 mutants designed in this study. Motifs I, II, and III conferring the ExoN active site are shown in green boxes. The Zinc fingers region is indicated in black box. The metal ion cooperating residues (D90, E92, E191, and D272), Zinc finger-related sites (C209 and H228), as well as other active sites involved in the study (N237, D242, and H267) are labeled in red. The introduced mutations are shown in blue. The numbers in gray indicate how many residues in PEDV-nsp14 are not shown. c 3D structural models for icPC22A nsp14. ExoN domain is circled. The metal ion cooperating residues (D90, E92, E191, and D272), Zinc finger-related sites (C209 and H228), as well as other active sites involved in the study (N237, D242, and H267) are labeled in red circles. d The predicted structural models for each mutation site and surrounding amino acids of wild type nsp14 and the mutants designed in this study