Extended Data Fig. 7: Allowing flexibility in the hinge region of the I32-10 trimer during docking renders plausible models of observed I32-10 assemblies.

(a) Comparison of (top) the design model with (bottom) the rigid bodies used for two-step docking into the experimental cryo-EM density maps. In the latter, the trimeric scaffold was cropped so that the helical bundle, which occupies the vertices of each architecture (dark blue), can be treated as a separate rigid body from the helical domains that form protein-protein interfaces with the dimeric scaffold (light blue). The entire light blue region in the bottom image, comprising the dimer with both neighboring helical domains from the trimer, was used as a single rigid body during docking. (b) Overlay of the I32-10 icosahedral design model (grey) with the corresponding built model (blue). (c) Example of a fit using a single rigid body derived from the design model into the D2 architecture (36 trimers + 54 dimers) cryo-EM density. The resulting model generates clashes at the center of the helical bundle (highlighted in red). (d) Situs metric95 for the built models. Models for the icosahedral (20 trimers + 30 dimers) and D2 (36 trimers + 54 dimers) architectures constructed using each method are compared.