POSTERS - BLAST X - University of Utah

BLAST X ______ Poster #5
DYNAMICS OF THE FLAGELLAR MOTOR PROTEIN FliM
Nicolas J. Delalez
Microbiology Unit, Biochemistry Dept, University of Oxford, South Parks Road, Oxford OX1
3QU, UK
Escherichia coli swims by rotating 4-6 long helical filaments to propel the cell through its
environment. The flagellar motor that rotates the filament is bidirectional and composed of two
parts: the rotor and the stator, the stator being the fixed component against which the rotor
spins. The stator is composed of units of two integral membrane proteins, MotA and MotB, the
stoichiometry of each unit being (MotA4:MotB2). The rotor is composed of multiple rings,
including the C-ring which is localized at the base of the motor and is the switch complex that
gives the bidirectionality to the E. coli motor. The C-ring comprises FliG (~ 25 copies), FliM (~34
copies) and FliN (> 100 copies).
By using a TIRF microscope, and expressing GFP-MotB from the genome of E. coli in
place of the wild-type gene, it has recently been possible to monitor the protein stoichiometry,
dynamics and turnover of this stator component with single-molecule precision in functioning
bacterial flagellar motors. Repeating these experiments with different flagellar motor proteins will
greatly enhance our understanding of the mechanism of this motor.
In particular, one of the main questions for our understanding is the mechanism of the
switching process. The C-terminus of FliM, a component of the C-ring, has therefore been
tagged with Ypet and expressed from the genome. Data will be presented on the construction of
this mutant as well as data on its dynamics, turnover and stoichoimetry, and the influence of the
response regulator CheY on these features. The consequences of these results and future work
will be discussed.
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