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Towards understanding how N-glycans of plant-produced SARS-CoV-2 spike protein influence binding to the ACE2 receptor by Marie Peeters -
Mardi 26 mai 2026 à 16h00 - Salle Jean-Baptiste Carnoy (B.059) - Bâtiment Carnoy - Croix du Sud - 1348 Louvain-la-Neuve -
SARS-CoV-2 emergence in late 2019 gave rise to an unprecedented pandemic. The initial step of SARS-CoV-2 infection consists of viral entry into host cells, mediated by the spike protein, by binding most notably to the ACE2 receptor on the host cell surface. The spike receptor binding domain (RBD) is, more specifically, responsible for this interaction. The SARS-CoV-2 spike protein contains 22 potential N-glycosylation sites per protomer. Its N-glycosylation profile plays a major role in modulating virion binding to ACE2.
Nicotiana tabacum Bright Yellow 2 (BY-2) suspension cells are commonly used in molecular farming for glycoprotein production. Previous work in our laboratory has generated several glycoengineered BY-2 cell lines. The XylT/FucT-KO cell line produces glycoproteins lacking β1,2-xylose and α1,3-fucose residues, while the GnTI/FucT-KO and Glycodelete cell lines yield glycoproteins with homogeneous high-mannose and single GlcNAc N-glycans, respectively.
This work aims to provide deeper insight into the role of the spike protein N-glycans in ACE2 receptor binding. The RBD from various SARS-CoV-2 variants was successfully secreted in the extracellular medium of glycoengineered BY-2 cell lines, yielding RBD glycovariants with defined N-glycosylation profiles. Fusion of a histidine tag to the RBD increased production levels, although the tag was cleaved from the protein, hampering purification.
Bio-layer interferometry (BLI) assays were successfully established to measure interactions between the different RBD glycovariants from unpurified BY-2 extracellular medium and ACE2, enabling to obtain preliminary binding kinetics data.
Finally, introducing an O-glycosylated linker before the histidine tag led to successful tag detection and RBD purification. Preliminary BLI experiments suggested that the presence of the linker did not prevent RBD-ACE2 interaction.
Jury members :
Prof. François Chaumont (UCLouvain) (Supervisor)
Dr Catherine Navarre (UCLouvain) (Supervisor)
Prof. Michel Ghislain (UCLouvain) (Chairperson)
Prof. Henri Batoko (UCLouvain) (Secretary)
Dr. Philippe Dehottay (GSK, Belg.)
Prof. Richard Strasser (Boku Univ., Austria)
Dr. Marylène Vandevenne (ULiège, Belg.)
Pay attention : the public defense of Marie Peeters will also take place in the form of a videoconference
