Abstract
FliG, FliM, and FliN, key proteins for torque generation, are
located in two rings. The first protein is in the M ring and the last
two are in the C ring. The rotational symmetries of the C and M rings
have been determined to be about 34 (this paper) and 26 (previous
work), respectively. The mechanism proposed here depends on the
symmetry mismatch between the rings: the C ring extends 34 levers, of
which 26 can bind to the 26 equivalent sites on the M ring. The
remaining 8 levers bind to proton–pore complexes (studs) to form 8
torque generators. Movement results from the swapping of stud-bound
levers with M ring-bound levers. The model predicts that both the M and
C rings rotate in the same direction but at different speeds.