Fig. 4: Rab10-induced conformational changes in the CC domain decrease the MO-CC stability.

a Overlay of the CC domain in its autoinhibited (orange) and Rab-activated (white) states. The overlay was generated by superimposing the CC domains from the previously reported crystal structure of the CC-Rab10 complex²⁶ and the cryo-EM structure from the current study. In the activated state, the CC domain exhibits a more planar arrangement of individual helices, whereas in the autoinhibited state, the CCα3 helix displays an axial tilt, which disturbs the CC planar arrangement. b The same CC domains as shown in (a) overlaid with the CH-L2α1-LIM assembly from the cryo-EM structure. This overlay demonstrates that the L2α1 helix maintains the CCα3 helix in the axially tilted conformation. c Further overlay of the structures from (b) with two Rab10 molecules from the previously reported CC-Rab10 complex²⁶. The low-affinity binding site of Rab10 overlaps with the CH-L2α1-LIM assembly, whereas Rab10 bound to the high-affinity site clashes with the axially tilted CCα3 helix. d Close-up view illustrating the shift of the proximal region of the CCα1 helix between the Rab-activated and autoinhibited states. In the Rab-activated state, the helix shifts away from the MO domain, disrupting critical interactions that stabilize the CC binding to the MO domain. e Detailed view highlighting differences in residue Arg933 between the activated and autoinhibited states. In the autoinhibited state, Arg933 in CCα1 forms a cation-π interaction with Phe399 from the MO domain, which is adjacent to Trp400, stabilizing FAD via coaxial stacking. Conversely, in the Rab-activated state, this cation-π interaction between Arg933 and Phe399 is disrupted.