NSP1 proteins from SARS-CoV-1 and SARS-CoV-2. (A) Protein sequence alignment of SARS-CoV-2 and SARS-CoV-1 NSP1 proteins. For SARS-CoV-1, only the divergent amino acids are shown. The amino acids are shown according to the following color code: negatively charged amino acids in pink, hydrophobic amino acids in blue, positively charged amino acids in green, aromatic amino acids in cyan, glycines and prolines in orange. Residues involved in interactions with ribosomal components are boxed in gray in SARS-CoV-2 (Schubert et al. 2020; Thoms et al. 2020; Yuan et al. 2020). Negative charge variations from SARS-CoV-2 to SARS-CoV-1 are indicated by blue squares, and positive charge variations are indicated by red squares. Residues that have been mutated in this study are boxed in black. The NSP1 proteins are subdivided in three domains, the amino-terminal domain, the central linker domain, and a carboxy-terminal domain. (B) Surface representation of crystal structure of SARS-CoV-2 NSP1 from residues E10 to L123 (PDB: 7K7P) (Clark et al. 2021) and NMR structure of SARS-CoV-1 NSP1 from residues H13 to G126 (PDB: 2HSX) (Almeida et al. 2007) from the front side (left panels) and from the back side (right panels). Both structures have been aligned and represented with the amino-terminal end in blue and the carboxy-terminal end in red. Divergent residues from SARS-CoV-1 that have been inserted in SARS-CoV-2 are circled in black. Next to each structure, the electrostatic surfaces of the protein with negative and positive charges are colored in red and blue, respectively. The position of residue R99 in SARS-CoV-2 NSP1 is indicated in red. (C) SDS PAGE analysis of purified recombinant wild-type SARS-CoV-1 and SARS-CoV-2 NSP1 proteins. (D) Linear representation of the three domains of NSP1, the Nt-domain in blue, the linker domain and the Ct-domain in red. The SARS-CoV-2 residues that have been mutated are marked. SDS PAGE analysis of purified recombinant wild-type and mutant SARS-CoV-2 NSP1 proteins.
