(A) The shape of nanodisc embedded Tar homodimer was characterized by single particle analysis and ET. Two flexible hinges was observed: HAMP hinge and the glycine hinge. (B) (Top) CryoET STA map of the CSU from in vitro reconstituted monolayer arrays at 8.4 Å resolution in top view and side view, overlaid with an MDFF-derived atomic model. Receptor in red, CheA in blue and CheW in gold. (Lower left) The ensemble of P4 conformations (red dots) using generalized simulated annealing (GSA). There are 12 medoid structures (black dots) from clustering of the ensemble, three of those are labeled as a, b and c, shown in the figure, illustrating the rigid body rotation of P4–P5 separation and P4 rotation. (Lower right) CheA-P3 interactions CheA-P5 (R315/D513, E280/ K608, R291/D628) and Tsr receptor (E319/R394). Basic amino acids are in blue, and acid amino acids are in red. (C) CryoET STA of CSU from lysed E. coli cells containing Tsr_EEEE and Tsr_QQQQ arrays, suggesting a ‘keel’ density (arrow) might be CheA-P1-P2 domains, and it is more mobile in kinase-on states (QQQQ). (D) CryoET STA of CSU from E. coli minicells containing wild-type arrays. Receptor domains are labeled as in Figure 1. The map was shown at different thresholds (0.0045 top and 0.018 bottom) separating by the dashed line. (E) Alternative chemosensory array lattice arrangement found in E. coli minicell, shown with atomic models (colors indicated in the key). Both the original and the alternative lattices are P2 lattices, with a unit cell containing three CSUs (original, left) or a single CSU (alternative, right). Panels are reproduced from [15,18,33,28,37] with permissions.