The effect of the D614G substitution on the structure of the spike glycoprotein of SARS-CoV-2

Significance The spike proteins of most current severe acute respiratory syndrome coronavirus 2 isolates contain a D614G substitution, by comparison with the spike protein of initial isolates. In this study we present high-resolution, single-particle cryo-electron microscopy structures of the G614 spike variant showing that it adopts a predominantly open conformation, unlike the D614 spike that is mostly closed. We conclude that the D614G substitution promotes “opening” of the spike, priming it for binding to the receptor ACE2 and possibly for its subsequent role in membrane fusion. The observed open conformation of the G614 spike may be the reason for the current virus’ reported increased infectivity and its current predominance.