Fig. 4: Structural analysis of the mutational tolerance of SARS-CoV-2 bFP and FPPR.

A Mutational tolerance of each residue in Calu-3 cells is shown on the NMR structure of the bFP and FPPR (PDB 7MY8)13. A disulfide bond (yellow in panel B) is present in the FPPR between Cys840 and Cys851. B The mutational tolerance of each residue in Calu-3 cells is shown. The locations of helices 1–3 in the NMR structure of the bFP and FPPR (PDB 7MY8)13 are indicated. The side chains of Leu828, Cys840, Asp848, and Cys851 are shown in stick representation.