Flagellar motors

Caplan S R and Kara-lvanov M 1993 The baoterial flagellar motor/nf. Rev. Cytol. 147 97-164... 

FIGURE 17. 33 A model of the flagellar motor assembly of Escherichia coli. The M ring carries an array of about 100 motB proteins at its periphery. These juxtapose with motA proteins in the protein complex that snrronnds the ring assembly. Motion of protons throngh the motA/motB complexes drives the rotation of the rings and the associated rod and helical filament. 

DeRo.sier, D. J., 1998. The turn of tire. screw The bacterial flagellar motor. CW/93 17-20. 

FIGURE 12-26 The two-component signaling mechanism in bacterial chemotaxis. When an attractant ligand (A) binds to the receptor domain of the membrane-bound receptor, a protein His kinase in the cytosolic domain (component 1) is activated and autophosphorylates on a His residue. This phosphoryl group is then transferred to an Asp residue on component 2 (in some cases a separate protein in others, another domain of the receptor protein). After phosphorylation on Asp, component 2 moves to the base of the flagellum, where it determines the direction of rotation of the flagellar motor. 

In its active form CheA undergoes autophosphorylation, that is, the phosphorylation of a histidine imidazole group in one of its subunits by the protein kinase active site of an adjacent subunit. The phospho group is then transferred from phospho-CheA to another protein, CheY. Phospho-CheY interacts with the flagellar motor proteins (Chapter 19) periodically causing a reversal of direction of the bacterial flagella. As a result the bacteria tumble and then usually move... 

Figure 19-3 Schematic drawing of bacterial flagellar motor. Based on drawings of Berg/7 Zhou and Blair/8 and Elston and Oster.1...

Subsequently, a readjustment of v( and vA occurs such that the concentration of X falls to its normal steady state level. X would act directly on the flagellar motor. 

The movement is processive, kinesin motors typically taking 100 steps before dissociating from the microtubule.201 2123 Kinesin is bound to the microtubule continuously. Its duty ratio is nearly 1.0 (the same is true for the bacterial flagellar motor ... 

Suzuki, H., Yonekura, K., and Namba, K. (2004). Structure of the rotor of the bacterial flagellar motor revealed by electron cryomicroscopy and single-particle image analysis./. Mol. Biol. 337, 105-113. 

Zhou, J., Lloyd, S. A., and Blair, D. A. (1998). Electrostatic interactions between rotor and stator in the bacterial flagellar motor. Proc. Natl. Acad. Sri. USA 95, 6436-6441. 

Atsumi, T., McCarter, L., and Imae, Y., Polar and lateral flagellar motors of marine Vibrio are driven by different ion-motive forces, Nature, 355, 182, 1992. 

The rotary nature of the bacterial flagellar motor was a startling, unexpected discovery. Unlike other systems that generate mechanical motion (muscles, for example) the bacterial motor does not directly use energy that is stored in a carrier molecule such as ATP. Rather, to... 

Figure 6.1 shows the structure of the flagellar motor in a simple illustration that reminds us of artificial machines. This machine-like motor is constructed through the self-assembly of proteins. The superior fimctionality and complexity of biological super molecules is quite apparent from this example. The energy for the rotation of the motor is provided by a proton flow from the outside to the inside of the bacteria. When an electrical potential difference is applied between the outside and the inside of the bacteria by immobilizing the bacterial cell on micropipette, the rotation speed can be controlled by al-... 

N.R. Francis, G.E. Sosinsky, D. Thomas, D.J. Derosier, Isolation, Characterization and Structure of Bacterial, Flagellar, Motors Containing the Switch Complex , J. Mol. Biol., 235, 1261 (1994)... 

Figure 34.30. Flagellar Motor. A schematic vieve of the flagellar motor, a complex structure containing as many as 40 distinct types of protein. The approximate positions of the proteins MotA and MotB (red), FliG (orange), FliN (yellow), and FliM (green) are shown.

Figure 34.31. Flagellar Motor Components. Approximately 30 subunits of FliG assemble to form part of the MS ring. The ring is surrounded by approximately 11 structures consisting of MotA and MotB. The carboxyl-terminal domain of FliG includes a ridge lined with charged residues that may participate in proton transport.

Figure 34.34. Chaugiug Direction. Tumbling is caused by an abrupt reversal of the flagellar motor, which disperses the flagellar bundle. A second reversal of the motor restores smooth swimming, almost always in a different direction. [After a drawing kindly provided by Dr. Daniel Koshland, Jr.]...

Backward rotation. On the basis of the proposed structure in Figure 34,32 for the bacterial flagellar motor, suggest a pathway for transmembrane proton flow when the flagellar motor is rotating clockwise rather than counterclockwise. 

S. C. Schuster and S. Khan. 1994. The bacterial flagellar motor Rev. Biophys. Biomol. Struct. 23 509-539. (PubMed)... 

W.S. Ryu, R.M. Berry, and H.C. Berg. 2000. Torque-generating units of the flagellar motor of Escherichia coli have a high duty ratio Nature 403 444-447. (PubMedl... 

S.A. Lloyd, F.G. Whitby, D.F. Blair, and C.P. Hill. 1999. Structure of the C-terminal domain of FliG, a component of the rotor in the bacterial flagellar motor Nature 400 472-475. (PubMedl... 

A protonmotive force across the plasma membrane is necessary to drive the flagellar motor. Under conditions of starvation, this protonmotive force is depleted. In acidic solution, the pH difference across the membrane is sufficient to power the motor. 

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