Structural basis of the American mink ACE2 binding by Y453F trimeric spike glycoproteins of SARS-CoV-2.
Ahn, H., Calderon, B.M., Fan, X., Gao, Y., Horgan, N.L., Jiang, N., Blohm, D.S., Hossain, J., Rayyan, N.W.K., Osman, S.H., Lin, X., Currier, M., Steel, J., Wentworth, D.E., Zhou, B., Liang, B.(2023) J Med Virol 95: e29163-e29163
- PubMed: 37842796 
- DOI: https://doi.org/10.1002/jmv.29163
- Primary Citation of Related Structures:  
8T20, 8T21, 8T22, 8T23, 8T25, 8TAZ - PubMed Abstract: 
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) enters the host cell by binding to angiotensin-converting enzyme 2 (ACE2). While evolutionarily conserved, ACE2 receptors differ across various species and differential interactions with Spike (S) glycoproteins of SARS-CoV-2 viruses impact species specificity. Reverse zoonoses led to SARS-CoV-2 outbreaks on multiple American mink (Mustela vison) farms during the pandemic and gave rise to mink-associated S substitutions known for transmissibility between mink and zoonotic transmission to humans. In this study, we used bio-layer interferometry (BLI) to discern the differences in binding affinity between multiple human and mink-derived S glycoproteins of SARS-CoV-2 and their respective ACE2 receptors. Further, we conducted a structural analysis of a mink variant S glycoprotein and American mink ACE2 (mvACE2) using cryo-electron microscopy (cryo-EM), revealing four distinct conformations. We discovered a novel intermediary conformation where the mvACE2 receptor is bound to the receptor-binding domain (RBD) of the S glycoprotein in a "down" position, approximately 34° lower than previously reported "up" RBD. Finally, we compared residue interactions in the S-ACE2 complex interface of S glycoprotein conformations with varying RBD orientations. These findings provide valuable insights into the molecular mechanisms of SARS-CoV-2 entry.
Organizational Affiliation: 
Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA.