Fusion mechanism of 2019-nCoV and fusion inhibitors targeting HR1 domain in spike protein

摘要

Study of the fusion mechanism of 2019-nCoV and characterization of a fusion inhibitor derived from the HR2 domain in spike protein of 2019-nCoV and a pan-CoV fusion inhibitor. Schematic representation of the 2019-nCoV S protein. SP signal peptide, RBD receptor-binding domain, RBM receptor-binding motif, FP fusion peptide, HR1 heptad repeat 1, HR2 heptad repeat 2, TM transmembrane domain, CP cytoplasm domain. The residue numbers of each region correspond to their positions in S protein of SARS-CoV and 2019-nCoV, respectively. The sequence alignment of HR1 core domains in SARS-CoV, SL-CoVs, and 2019-nCoV. Sequences of 2019-nCoV-HR1P, 2019-nCoV-HR2P, SARS-HR2P, and EK1. Determination of the interactions between 2019-nCoV-HR1P and 2019-nCoV-HR2P. Bands of 2019-nCoV-HR2P are highlighted in red box; the blue arrows indicate the bands of 6-HB. Circular dichroism (CD) spectra of 2019-nCoV-HR1P, 2019-nCoV-HR2P, and 2019-nCoV-HR1P/2019-nCoV-HR2P complex. Melting curves of the 2019-nCoV-HR1P/2019-nCoV-HR2P complex. Inhibitory activity of peptides on 2019-nCoV S-mediated cell–cell fusion. Determination of the interactions between 2019-nCoV-HR1P and EK1. Bands of EK1 are highlighted in green box; the blue arrows indicate the bands of 6-HB. CD spectra of 2019-nCoV-HR1P, EK1, and 2019-nCoV-HR1P/EK1 complex. Inhibition of peptides on pseudotyped 2019-nCoV infection. The putative antiviral mechanism of 2019-nCoV-HR2P and EK1. After binding of RBD in S1 subunit of 2019-nCoV S protein to the potential receptor ACE2 on the host cell, S2 subunit changes conformation by inserting FP into the cell membranes and triggering the association between the HR1 and HR2 domains to form 6-HB, which brings the viral and cellular membranes in close proximity for fusion (left part of ). In the presence of 2019-nCoV-HR2P or EK1 peptide, three copies of the peptide bind to the 2019-nCoV S-HR1-trimer to form heterologous 6-HB, thus blocking the formation of viral homologous 6-HB and thus inhibiting viral and cell membrane fusion (right part of )