Article,
Two Receptor Binding Strategy of SARS-CoV-2 Is Mediated by Both the N-Terminal and Receptor-Binding Spike Domain
Affiliations
- [1] Ist Italiano Tecnol IIT, Ctr Human Technol CHT, RNA Syst Biol, I-16152 Genoa, Italy [NORA names: Italy; Europe, EU; OECD];
- [2] Sapienza Univ, Dept Phys, I-00185 Rome, Italy [NORA names: Italy; Europe, EU; OECD];
- [3] Groningen Biomol Sci & Biotechnol, Mol Immunol, NL-9747 AG Groningen, Netherlands [NORA names: Netherlands; Europe, EU; OECD];
- [4] CNR, Ist Sci Patrimonio Culturale, DHILab, Sede Roma, I-00010 Rome, Italy [NORA names: Italy; Europe, EU; OECD];
- [5] CNR, Ist Sci Patrimonio Culturale, DHILab, Sede Roma, I-00010 Rome, Italy [NORA names: Italy; Europe, EU; OECD];
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Abstract
It is not well understood why severe acute respiratory syndrome (SARS)-CoV-2 spreads much faster than other beta-coronaviruses such as SARS-CoV and Middle East respiratory syndrome (MERS)-CoV. In a previous publication, we predicted the binding of the N-terminal domain (NTD) of SARS-CoV-2 spike to sialic acids (SAs). Here, we experimentally validate this interaction and present simulations that reveal a second possible interaction between SAs and the spike protein via a binding site located in the receptor-binding domain (RBD). The predictions from molecular-dynamics simulations and the previously-published 2D-Zernike binding-site recognition approach were validated through flow-induced dispersion analysis (FIDA)& horbar;which reveals the capability of the SARS-CoV-2 spike to bind to SA-containing (glyco)lipid vesicles, and flow-cytometry measurements & horbar;which show that spike binding is strongly decreased upon inhibition of SA expression on the membranes of angiotensin converting enzyme-2 (ACE2)-expressing HEK cells. Our analyses reveal that the SA binding of the NTD and RBD strongly enhances the infection-inducing ACE2 binding. Altogether, our work provides in silico, in vitro, and cellular evidence that the SARS-CoV-2 virus utilizes a two-receptor (SA and ACE2) strategy. This allows the SARS-CoV-2 spike to use SA moieties on the cell membrane as a binding anchor, which increases the residence time of the virus on the cell surface and aids in the binding of the main receptor, ACE2, via 2D diffusion.