Fig. 1: Overall structure of the HCoV-229E spike in the prefusion conformation.

a Schematic diagram of the HCoV-229E S glycoprotein organization. S1 receptor-binding subunit, S2 membrane fusion subunit, NTD N-terminal domain, blue, L linker region, yellow, RBD receptor-binding domain, magenta, SD1 subdomain1, cyan, SD2 subdomain2, green, UH upstream helix, pink, FP fusion peptide, red, CR connecting region, yellow, HR1 heptad repeat 1, orange, CH central helix, purple, CD connector domain, aquamarine, HR2 heptad repeat 2, TM transmembrane domain, CT cytoplasmic tail, the range of FP used to make the figures is consistent with that of a previous structural study on the MHV spike¹⁸. The black line boxes denote the regions that are unresolved in the density map (HR2) or not part of the construct (TM and CT). b, c The orthogonal views of the S protein in conformations 1 and 2. The protomer A, B, and C are colored as cyan, magenta, and green, respectively. The length of conformations 1 and 2 is measured via the PyMOL. d, e The atomic structures of conformations 1 and 2 are shown as ribbon diagrams oriented as in (b) and (c). The domains are indicated and colored as defined in Fig. 1a.