Extended Data Fig. 6: Inherent structural flexibility is sufficient to build high-quality models of the observed assemblies.

(a,b) Overlay of the snapshots used to build each model for KWOCAs 18 and 70, respectively. Rigid bodies extracted from the design models are colored in grey. In addition to full snapshots (left), overlays of all individual chains aligned to the helical bundle or the protein interface are shown to highlight the flexibility in the fusion region (right). (c,d) Models built by fitting (top row, color) snapshots extracted from the MD trajectories or (bottom row, grey) rigid bodies extracted from the design models into the experimental cryo-EM density maps for KWOCAs 18 and 70, respectively. Insets highlight regions where the fits of the MD snapshots are clearly superior to those from the design models. (e) RMSDs between fitted trimeric and dimeric building blocks at the stitching region where the bars represent the maximum value (see Methods for details) and (f) the overall fit of the model to the cryo-EM density using rigid bodies from the design model or snapshots from the MD trajectories both highlight the higher quality of the models constructed from the MD snapshots.