Fig. S8.

Interaction between FliT and FliI. (A) Structure of FliI (PDB ID code 2DPY). The extreme N-terminal region was not crystallographically resolved and is modeled here as an unstructured region. (B) Stepwise titration of unlabeled FliI to U-²H–,¹⁵N Ala-¹³CH₃–, Met-¹³CH₃–, Ile-δ1-¹³CH₃–, Leu,Val-¹³CH₃/¹³CH₃–labeled FliT. (C) The FliT residues affected by FliI binding are colored red on the FliT surface. (D) NMR spectra show that the FliI^Δ17 variant does not bind to FliT. (E) ATPase activity of FliI, FliI^Δ17, and FliI in complex with FliT. The ATPase activity is expressed in nanomoles of hydrolyzed ATP per microgram of protein. (F) ¹H-¹⁵N HSQC spectra of FliT−FliI^EN (orange) and FliT^Δα4−FliI^EN (blue) complexes show very similar chemical shifts.