Flagellar motion

E. coli convert electromotive force to proton-motive force, which is then used to power flagellar motion. 

Ringo, D. J. (1967) Flagellar motion and fine structure of the flagellar apparatus in Chlamydomonas. J. Cell Biol. 33, 543-571. 

Stephens, D.T. and Hoskins, D.D. (1990). Gomputerized quantitation of flagellar motion in mammalian sperm, in Controls of Sperm Motility Biological and Clinical Aspects (G. Gagnon, ed.), pp. 251-260. GRG Press, Boca Raton, FL. 

The flagellum does not contain all of the components necessary for flagellar rotation. Mutation of either the motA or motB genes leads to the production of paralysed flagella that appear otherwise normal. These two membrane proteins (M, motA = 33,000, mot 39,000) may provide the energisation necessary for flagellar motion. 

It is interesting that Peter Mitchell also conceived of the correct model for bacterial flagellar motion as being driven by a rotating proton motor, a concept later applied to the mechanism of the F,Fo ATPase. 

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. 

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... 

Explain the role of proton-motive force in flagellar rotation. Present a model that explains the production of rotary motion from the effects of a proton gradient on the transmembrane flagellar motor. 

With the exception of some cyanobacteria that swim by rippling their outer membrane (7) Eubacteria and Archaea overcome the reciprocal motion problem by rotating helical flagellar filaments (8). Flagella almost certainly evolved independently but convergently in those two domains of life (9). Spirochetes hide the flagellar filaments between their inner and outer membranes, so that flagellar rotation causes the entire sinusoid or helical body to serve as the propeller (10). 

In our view, cyclic protonation/deprotonation of carboxylates drives the cyclic association/ dissociation of oil-like groups responsible for flagellar rotary motion and for rotation of an asymmetric oil-like rotor to produce ATP by ATP synthase. In the process, protons move from the high concentration to the low concentration side of a cell membrane in which the membrane component of the rotary motor resides. In fact, the proton concentration difference from one side to the other of the mem-... 

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