Natural variations within the glycan shield of SARS-CoV-2 impact viral spike dynamics

Abstract

The emergence of SARS-CoV-2 variants alters the efficacy of existing immunity, whether arisen naturally or through vaccination. Understanding the structure of the viral spike assists in determining the impact of mutations on the antigenic surface. One class of mutation impacts glycosylation attachment sites, which have the capacity to influence the antigenic structure beyond the immediate site of attachment. Here, we compare the glycosylation of a recombinant viral spike mimetic of the P.1 (Gamma) strain, which exhibits two additional N-linked glycan sites compared to the equivalent mimetic of the Wuhan strain. We determine the site-specific glycosylation of these variants and investigate the impact of these glycans by molecular dynamics. The N188 site is shown to exhibit very limited glycan maturation, consistent with limited enzyme accessibility. Structural modeling and molecular dynamics reveal that N188 is located within a cavity by the receptor binding domain, which influences the dynamics of these attachment domains. These observations suggest a mechanism whereby mutations affecting viral glycosylation sites have a structural impact across the antigenic surface.