Fig. 1: SARS-CoV-2 MBP interacts with lipid vesicles.

a Cartoon illustrating the interaction between SARS-CoV-2 and the host membrane. The S protein binds to the host cell surface via ACE2 receptor, and upon host proteases activation, the S1 subunit detaches, exposing the MBP. The exposed MBP then binds to the host membrane, followed by refolding of S2 into a post-fusion state, leading to the membrane fusion between virus and target cells. b, c Ribbon diagrams of MBP1 and MBP2 respectively, predicted by AlphaFold2 and equilibrated using a molecular dynamics protocol. d The sequence of the MBP region of SARS-CoV-2 spans amino acid residues 816-855 of the S protein sequence. MBP1 and MBP2 are tagged with LPETGG at the C-terminus, and MBP2 is extended by an additional 11 amino acid residues at the N-terminus, mimicking the uncleaved peptide. Biolayer interferometry sensorgrams depicting the real-time binding of SARS-CoV-2 MBP and lipid vesicles consisting of DOPC and Chol (e) or DOPC and SM (f). Grey lines represent the raw data, while colored lines represent the binding rate of the association phase, which is the linear fit within the preliminary 60 s of the association phases. Biolayer interferometry sensorgrams show the comparison of the binding of MBP1 or MBP2 to the lipid vesicles. MBP1 or MBP2 (10 µM) were loaded onto the sensors and were then allowed to interact with the 1 mM DOPC/Chol vesicle (g) or DOPC/SM vesicle (h), respectively. Source data for panels e-h are provided as a Source Data file.