Oral Presentation 28th Annual Lorne Proteomics Symposium 2023

Glycosylation of the SARS-CoV-2 Gamma spike protein (#49)

Cassandra Pegg 1 , Naphak Modhiran 1 , Daniel Watterson 1 , Benjamin Schulz 1
  1. The School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD, Australia

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) - the cause of the ongoing COVID-19 pandemic - has the capacity to generate variants with major antigenic changes in the surface exposed spike glycoprotein. The emergence of SARS-CoV-2 viral variants threatens current anti-viral and preventative strategies, including monoclonal antibodies and vaccines. The trimeric spike protein of SARS-CoV-2 mediates binding to and fusion with host cells and is covered with a “glycan shield” of ~66 N-glycosylation sites per trimer. Glycosylation is required for efficient folding and maturation of the spike proteins, and the specific glycan structures on the viral proteins can control their interactions and thereby the specificity of viral infectivity and immune evasion. To gain a better understanding of the role glycosylation plays in SARS-CoV-2 we investigated the glycosylation profile of a recently emerged Gamma variant which has mutations that introduce two new N-glycosylation sequons. We expressed and purified the original Wuhan spike, the Gamma variant and a combination of variants from CHO cells, and performed glycoproteomic analysis, which showed changes to their site-specific N-glycosylation occupancy and structural heterogeneity. We observed site swapping with the introduction of a downstream N-linked sequon at position 20 in the spike protein of SARS-CoV-2. Our work also revealed that sequence changes in the spike proteins can dramatically alter the glycosylation profile of the protein. This work highlights the difference in glycosylation of the spike protein between variants which can be used to inform therapeutic strategies.