Comparative analysis reveals the species specific genetic determinants of ACE2 required for SARS CoV 2 entry

Author summarySARS-CoV-2 spike protein could bind cellular receptor ACE2 for cell entry in a species-specific manner. A diverse of mammalian ACE2 proteins could be used by SARS-CoV-2 for entry, but ACE2 proteins of koala or mouse cannot bind with viral spike protein. We compared the koala or mouse ACE2 with human ACE2, and found Thr at 31 position of koala ACE2 or His at 353 position of mouse ACE2 as the restrictive residue which limits its function as the viral receptor, respectively. Interestingly, koala or mouse ACE2 could gain the receptor function once the restrictive reside was replaced by human counterpart by genetic engineering. This study could facilitate our understanding of the genetic basis of ACE2 as the functional receptor of SARS-CoV-2, which could inform the animal model development.Coronavirus interaction with its viral receptor is a primary genetic determinant of host range and tissue tropism. SARS-CoV-2 utilizes ACE2 as the receptor to enter host cell in a species-specific manner. We and others have previously shown that ACE2 orthologs from New World monkey, koala and mouse cannot interact with SARS-CoV-2 to mediate viral entry, and this defect can be restored by humanization of the restrictive residues in New World monkey ACE2. To better understand the genetic determinants behind the ability of ACE2 orthologs to support viral entry, we compared koala and mouse ACE2 sequences with that of human and identified the key residues in koala and mouse ACE2 that restrict viral receptor activity. Humanization of these critical residues rendered both koala and mouse ACE2 capable of binding the spike protein and facilitating viral entry. Our study shed more lights into the genetic determinants of ACE2 as the functional receptor of SARS-CoV-2, which facilitates our understanding of viral entry.