Structural basis of the American mink ACE2 binding by Y453F
trimeric spike glycoproteins of SARS-CoV-2
Hyunjun Ahn1#, Brenda M.
Calderon2,3#, Xiaoyu Fan2,3#,
Yunrong Gao1#, Natalie L. Horgan1,
Nannan Jiang2,3, Dylan S. Blohm1,
Jaber Hossain2,3, Nicole Wedad K. Rayyan1, Sarah H.
Osman2,4, Xudong Lin2,3, Michael
Currier2,3, John Steel3, David E.
Wentworth2,3, Bin Zhou2,3*, Bo
Liang1*
1Department of Biochemistry, Emory University School
of Medicine, Atlanta, GA, 30322 United States
2COVID-19 Emergency Response, Centers for Disease
Control and Prevention, Atlanta, GA 30329
3Influenza Division, National Center for Immunization
and Respiratory Diseases, Centers for Disease Control and Prevention,
Atlanta, GA 30329
4Division of
Laboratory Sciences, National Center for Environmental Health, Centers
for Disease Control and Prevention, Chamblee, GA, 30341
# These authors contributed equally to this study.
* Correspondence:
bo.liang@emory.edu and
bzhou@cdc.gov
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 glycoproteins 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
glycoproteins. 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 glycoprotein 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.