Figure 5.

Structures and proposed conformational changes of SARS-CoV S2.

(a) Close-up view of S2 in the prefusion (left) and postfusion (right) conformations from PDB ID: 6XR8 and 6XRA, with the fusion peptide (FP) highlighted in purple, the FPPR in red, central helix (CH) in gold, connector domain (CD) in green, HR1 in orange and HR2 in green. (b) Proposed structural transition of the HR1 from the prefusion to postfusion conformation. (c) Proposed conformational change of the HR2. (d). Six-helix bundle structures in the postfusion S2 with HR1 in orange and HR2 in green.