Sequential Glycosylations at the Multibasic Cleavage Site of SARS-CoV-2 Spike Protein Regulate Viral Activation, Assembly, and Infection

ABSTRACT: The multibasic furin cleavage site at the S1/S2 boundary of the spike protein (S protein) is a hallmark of SARS-CoV-2 and plays an crucial role in viral infection. O-glycosylation near the furin site catalyzed by host cell glycosyltransferases can theoretically hinder spike protein processing and impede viral infection, but so far such a hypothesis has not been tested with authentic viruses. The mechanism underlying furin activation also remains poorly understood. In this study, we have discovered that GalNAc-T3 and T7 jointly initiate clustered O-glycosylations in the multibasic S1/S2 boundary region. These O-glycosylations inhibit furin processing of the spike protein and surprisingly suppress the incorporation of S protein into virus-like-particles (VLPs). Mechanistic analysis revealed that the assembly of spike protein into VLPs relies on protein-protein interaction between the furin-cleaved S protein and a double aspartic motif on the membrane protein of SARS-CoV-2, suggesting a novel mechanism for furin activation of the S protein. Interestingly, a point mutation at P681, found in the alpha and delta variants of SARS-CoV-2, confers resistance to glycosylation by GalNAc-T3 and T7, thereby diminishing the inhibitory effect against furin processing. However, an additional mutation at N679 in the most recent omicron variant reverses this resistance, rendering it susceptible to glycosylation in vitro and sensitive to the expression of GalNAc-T3 and T7 in human lung cells. Together, our findings suggest a glycosylation-based defense mechanism employed by host cells against SARS-CoV-2 and unveil the intricate interplay between the host and pathogen at this critical “battlefield” as the virus initially evades and currently succumbs to host cell glycosylation..

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: YUYU YOU  

LAB HEAD: Mao Yang

PROVIDER: PXD049110 | Pride | 2024-03-21

REPOSITORIES: Pride