2015 年 57 巻 5 号 p. 291-296
Bacteria swim in aqueous environment by rotating the flagellum driven by a reversible motor embedded in the cell membrane. The torque of the motor is generated by the rotor-stator interaction coupled with the ion flow through the stator. A dozen of stators assemble around the rotor and are fixed to the peptidoglycan layer. The ion-conductivity of the stator is coupled to its assembly, and proper anchoring of the stator is required for torque generation. We determined the crystal structures of C-terminal fragments of the B-subunit of the stator including the region responsible for anchoring the stator, and performed the functional analyses using the mutants designed based on the structure. These studies revealed that the conformational change of the N-terminal region of the fragment is essential to form a functional stator around the rotor.