Nanometer-resolution in situ structure of the SARS-CoV-2 postfusion spike protein
Linhua Tai, Guoliang Zhu, Minnan Yang, Lei Cao, Xiaorui Xing, Guoliang Yin, Chun Chan, Cheng‐Feng Qin, Zihe Rao, Xiangxi Wang, Fei Sun, Yun Zhu
Abstract
The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mediates membrane fusion to allow entry of the viral genome into host cells. To understand its detailed entry mechanism and develop a specific entry inhibitor, in situ structural information on the SARS-CoV-2 spike protein in different states is urgent. Here, by using cryo-electron tomography, we observed both prefusion and postfusion spikes in β-propiolactone-inactivated SARS-CoV-2 virions and solved the in situ structure of the postfusion spike at nanometer resolution. Compared to previous reports, the six-helix bundle fusion core, the glycosylation sites, and the location of the transmembrane domain were clearly resolved. We observed oligomerization patterns of the spikes on the viral membrane, likely suggesting a mechanism of fusion pore formation.