Structures and distributions of SARS-CoV-2 spike proteins on intact virions
Zunlong Ke, Joaquin Oton, Kun Qu, Mirko Cortese, Vojtech Zila, Lesley McKeane, Takanori Nakane, Jasenko Zivanov, Christopher J. Neufeldt, Berati Cerikan, John M. Lu, Julia Peukes, Xiaoli Xiong, Hans-Georg Kräusslich, Sjors H. W. Scheres, Ralf Bartenschlager & John A. G. Briggs
Nature (2020)
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virions are surrounded by a lipid bilayer from which spike (S) protein trimers protrude1. Heavily glycosylated S trimers bind the ACE2 receptor and mediate entry of virions into target cells2–6. S exhibits extensive conformational flexibility: it modulates exposure of its receptor binding site and later undergoes complete structural rearrangement to drive fusion of viral and cellular membranes2,7,8. The structures and conformations of soluble, overexpressed, purified S proteins have been studied in detail using cryo-electron microscopy2,7,9–12. The structure and distribution of S on the virion surface, however, has not been characterized. Here we applied cryo-electron microscopy and tomography to image intact SARS-CoV-2 virions, determining the high-resolution structure, conformational flexibility and distribution of S trimers in situ on the virion surface. These results reveal the conformations of S present on the virion, and provide a basis from which to understand interactions between S and neutralizing antibodies during infection or vaccination.