Protein dynamics and mechanisms controlling the rotational behaviour of the bacterial flagellar motor

The proteins that make up the bacterial flagellar rotary motor have recently been shown to be more dynamic than previously thought, with some key proteins exchanging with pools of proteins in the membrane/cytoplasm. It has also become clear that in addition to simply switching in response to chemosensory signals, the rotation of the bacterial flagellar motor can be slowed or stopped, using a clutch or a brake, by signals from metabolism and growth state.

► This review focuses on protein turnover and mechanisms controlling the output of the bacterial flagellar motor.
► MotA–MotB stator units and the switch protein FliM turnover rapidly while other motor components turnover slowly, for example FliN, or do not turnover at all, for example FliG and FliF.
► The output of the flagellar motor is controlled by a growing list of effector proteins, for example CheY, H-NS, FRD, YcgR, EpsE.