PT  - JOURNAL ARTICLE
AU  - Rachael A. Mansbach
AU  - Srirupa Chakraborty
AU  - Kien Nguyen
AU  - David C. Montefiori
AU  - Bette Korber
AU  - S. Gnanakaran
TI  - The SARS-CoV-2 Spike Variant D614G Favors an Open Conformational State
AID  - 10.1101/2020.07.26.219741
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.07.26.219741
4099  - http://biorxiv.org/content/early/2020/07/26/2020.07.26.219741.short
4100  - http://biorxiv.org/content/early/2020/07/26/2020.07.26.219741.full
AB  - The COVID-19 pandemic underwent a rapid transition with the emergence of a SARS-CoV-2 variant that carried the amino acid substitution D614G in the Spike protein that became globally prevalent. The G-form is both more infectious in vitro and associated with increased viral loads in infected people. To gain insight into the mechanism underlying these distinctive characteristics, we employed multiple replicas of microsecond all-atom simulations to probe the molecular-level impact of this substitution on Spike’s closed and open states. The open state enables Spike interactions with its human cellular receptor, ACE2. Here we show that changes in the inter-protomer energetics due to the D614G substitution favor a higher population of infection-capable (open) states. The inter-protomer interactions between S1 and S2 subunits in the open state of the D-form are asymmetric. This asymmetry is resolved in the G-form due to the release of tensile hydrogen bonds resulting in an increased population of open conformations. Thus, the increased infectivity of the G-form is likely due to a higher rate of profitable binding encounters with the host receptor. It is also predicted to be more neutralization sensitive due to enhanced exposure of the receptor binding domain, a key target region for neutralizing antibodies.Competing Interest StatementThe authors have declared no competing interest.