Roles of the Escherichia coli proteins FliG, FliM, and FliN in flagellar rotation

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Many bacteria are propelled by reversible rotary motors which derive the energy for rotation from a protonmotive gradient. Among the many proteins required to build a fully functional motor, there are five, called MotA, MotB, FliG, FliM, and FliN, that are most likely to be involved in torque generation. FliG, FliM, and FliN are also important for assembly and for determining the direction of rotation; these are called "switch-complex" proteins. The roles of the switch-complex proteins in torque generation will be examined, using molecular genetics to make mutations in these components, and detailed measurements of motor performance to assess the consequences. The effects of controlled, low-level expression of theses proteins also will be examined. This strategy is similar to that used previously to study MotA and MotB. The long-term objective of these studies is to understand, at the molecular level, how the flagellar motor converts chemical energy into mechanical energy. Understanding mechanisms of energy conversion is a central concern in bioenergetics. Also since motility plays a role in certain bacterial infections, understanding the flagellar motor is likely to have clinical significance.