Exceptional diversity and selection pressure on SARS-CoV and SARS-CoV-2 host receptor in bats compared to other mammals

Hannah K. Frank; David Enard; Scott D. Boyd

CoV-2 by giving a score to each amino acid in each position. Residues that were identical or 330 relatively equivalent to humans were given a score of 1; relative equivalency was inferred when 331 amino acids retained similar properties and abilities to participate in hydrogen bonds, Van der 332 Waals forces or salt bridges. Residues that would likely be worse at binding were given scores 333 of -1; reduced binding was inferred when amino acid properties were dramatically altered from 334 that of the human amino acid motif (e.g. replacement of a positively charged amino acid with a 335 negatively charged amino acid in a salt bridge). In general, asparagine and glutamine were 336 considered similar enough not to disrupt binding, as were amino acids with the same charge 337 and amino acids with small hydrophic side chains (valine, leucine, isoleucine and methionine).