Rotation of Flagella

A Proton Gradient Drives die Rotation of Bacterial Flagella... 

FIGURE 19-34 Rotation of bacterial flagella by proton-motive force. 

The shaft and rings at the base of the flagellum make up a rotary motor that has been called a "proton turbine." Protons ejected by electron transfer flow back into the cell through the turbine, causing rotation of the shaft of the flagellum. This motion differs fundamentally from the motion of muscle and of eukaryotic flagella and cilia, for which ATP hydrolysis is the energy source. 

Figure 19-5 Schematic representation of an important chemotactic system of E. coli, S. typhimurium, and other bacteria. The transmembrane receptor activates the autokinase CheA, which transfers its phospho group to proteins CheY and CheB to form CheY-P and CheB-P. CheY-P regulates the direction of rotation of the flagella, which are distributed over the bacterial surface. CheR is a methyltransferase which methylates glutamate carboxyl groups in the receptor and modulates the CheA activity. CheZ is a phosphatase and CheB-P a methylesterase.

Figure 2.20. Bacteria with Flagella. A bacterium Proteus mirabilis) swims through the rotation of filamentous structures called flagella. [Fred E. Hossler/Visuals Unlimited.]... 

In chemiosmotic coupling, a proton-motive force powers an energy-requiring process such as ATP synthesis (A), transport of metabolites across the membrane against their concentration gradient (B), or rotation of bacterial flagella (C). 

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