(A) Phylogenetic tree based on 283 sequences from distinct α- and β-coronaviruses (CoVs) of different subgenera. The sequences were obtained from the Conserved Domain Database (CDD) with accession number cl41742. The scale bar indicates the number of substitutions per site in the amino acid sequence. Six different Nsp1 domain models can be identified, two for the α-CoVs (transmissible gastroenteritis virus [TGEV]-like and PDEV-like), and four for the β-CoVs genus (MERS-like, HKU9-like, SARS-like, and murine hepatitis virus [MHV]-like). (B) Multi-sequence alignment of the four homologues selected. The alignment was performed with the MUSCLE algorithm (Edgar, 2004). The residues of the different pockets are highlighted in the corresponding color, namely pocket 1 in purple, pocket 2 in green, pocket 3 in orange, and pocket 4 in cyan. (C) Representation of the pockets found in the severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) Nsp1N variant.