Fig. 3: Structural analysis of the FlhB hydrophobic ___domain.

a Quality of the cryo-EM volume corresponding to FlhB. Zoom box shows the fit to density of the model. b, c Rainbow colouring of the FlhB model with numbers indicating the N and C termini of the four helices. d Evolutionary co-variation within FlhB calculated using RaptorX46. Only contacts with a probability >0.5 are plotted. Red boxes highlight the interaction between helix 1 and 2 (i), helix 1 and 4 (ii), helix 3 and 4 (iii), the N terminus and FlhBCN (iv), within the N terminus (v) and between FlhBL and the N terminus (vi). e Overlay of FlhB (green) and a modelled FliQ5 and FliQ6 following the same helical parameters as FliQ1 to FliQ4 in V. mimicus. f Zoomed view of the interaction between the FlhB loop and FliQ, highlighting the intercalation of conserved hydrophobic residues in FlhB between the FliQ subunits.