Stabilized coronavirus spikes are resistant to conformational changes induced by receptor recognition or proteolysis

• Published in: Scientific reports Vol. 8; no. 1; pp. 15701 - 11
• Main Authors: Kirchdoerfer, Robert N., Wang, Nianshuang, Pallesen, Jesper, Wrapp, Daniel, Turner, Hannah L., Cottrell, Christopher A., Corbett, Kizzmekia S., Graham, Barney S., McLellan, Jason S., Ward, Andrew B.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.10.2018; Nature Publishing Group
• Subjects: 101/28; 631/326/596/2078; 631/535/1258/1259; 82/103; 82/80; 82/83; ACE2; Angiotensin; Angiotensin-Converting Enzyme 2; Binding Sites; Coronaviridae; Coronaviruses; COVID-19; Cryoelectron Microscopy; Fusion protein; Glycosylation; HEK293 Cells; Humanities and Social Sciences; Humans; multidisciplinary; Mutation; Peptide Hydrolases - chemistry; Peptidyl-Dipeptidase A - chemistry; Proline - genetics; Protein Stability; Protein Structure, Secondary; Proteolysis; Receptors, Virus - chemistry; SARS Virus - chemistry; Science; Science (multidisciplinary); Severe acute respiratory syndrome; Spike glycoprotein; Spike Glycoprotein, Coronavirus - chemistry; Tropism; Trypsin; Trypsin - chemistry; Viral Tropism; Virus Internalization; Secondary Cleavage Sites; ACE2 Receptor; Severe Acute Respiratory Syndrome Coronavirus; Angiotensin-converting Enzyme (ACE2); Middle East Respiratory Syndrome Coronavirus (MERS-CoV)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-34171-7

Severe acute respiratory syndrome coronavirus (SARS-CoV) emerged in 2002 as a highly transmissible pathogenic human betacoronavirus. The viral spike glycoprotein (S) utilizes angiotensin-converting enzyme 2 (ACE2) as a host protein receptor and mediates fusion of the viral and host membranes, making S essential to viral entry into host cells and host species tropism. As SARS-CoV enters host cells, the viral S is believed to undergo a number of conformational transitions as it is cleaved by host proteases and binds to host receptors. We recently developed stabilizing mutations for coronavirus spikes that prevent the transition from the pre-fusion to post-fusion states. Here, we present cryo-EM analyses of a stabilized trimeric SARS-CoV S, as well as the trypsin-cleaved, stabilized S, and its interactions with ACE2. Neither binding to ACE2 nor cleavage by trypsin at the S1/S2 cleavage site impart large conformational changes within stabilized SARS-CoV S or expose the secondary cleavage site, S2′.