Flagellum bacterial

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

Boltjes came to the following conclusions on the staining of bacterial flagella ... 

This theory clearly predicts that the shape of the polymer length distribution curve determines the shape of the time course of depolymerization. For example Kristofferson et al. (1980) were able to show that apparent first-order depolymerization kinetics arise from length distributions which are nearly exponential. It should also be noted that the above theory helps one to gain a better feeling for the time course of cytoskeleton or mitotic apparatus disassembly upon cooling cells to temperatures which destabilize microtubules and effect unidirectional depolymerization. Likewise, the linear depolymerization kinetic model could be applied to the disassembly of bacterial flagella, muscle and nonmuscle F-actin, tobacco mosaic virus, hemoglobin S fibers, and other linear polymers to elucidate important rate parameters and to test the sufficiency of the end-wise depolymerization assumption in such cases. 

The mechanochemical rotatory motion of bacterial flagella, driven by electrochemical proton gradients across the peripheral membrane. Each complete turn requires... 

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

Detailed review of the structures that underlie proton-driven rotary motion of ATP synthase and bacterial flagella. 

Compare the chemical makeup of ribosomes, of cell membranes, and of bacterial flagella. 

Small viruses, bacterial flagella, ribosomes, and even molecules can be seen by electron microscopy. However, to obtain a clear image in three dimensions requires a computer-based technique of image reconstruction or electron microscope tomography, which was developed initially by Aaron Klug and associates.344-349 A sample is mounted on a goniometer, a device that allows an object to be tilted at exact angles. Electron... 

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... 

There is probably no biological phenomenon that has excited more interest among biochemists than the movement caused by the contractile fibers of muscles. Unlike the motion of bacterial flagella, the movement of muscle is directly dependent on the hydrolysis of ATP as its source of energy. Several types of muscle exist within our bodies. Striated (striped) skeletal muscles act under voluntary control. Closely related are the involuntary striated heart muscles, while smooth involuntary muscles constitute a third type. Further distinctions are made between fast-twitch and slow-twitch fibers. Fast-twitch fibers have short isometric contraction times, high maximal velocities for shortening, and high rates of ATP hydrolysis. 

Parallels between everyday mechanisms and cellular processes extend also to myosin head groups racheting to actin subunits to produce the sliding filaments of skeletal muscle (see Perry, 1997), rotary motors for bacterial flagella (see Armitage, 1997) or movements along microtubules, powered by the proton motive force or ATP (see also Block, 1997). The existence of a mitochondrial rotary motor has recently been established. Boyer s proposal that the y subunit of the mitochondrial ATP synthase rotated within the other subunits has been vindicated by X-ray crystallography (Walker, 1997) and direct demonstration of the rotation. 

Another example of a rotary motor is that of bacterial flagella, 23 which are responsible for bacterial motility. 

Westerlund-Wikstrom, B. (2000) Peptide display on bacterial flagella principles and applications. Int. J. Med. Microbiol. 290, 223-230. 

All present day cilia and (eukaryotic, not bacterial] flagella, motile or not, clearly evolved from the 9+2 versions. The rarely encountered motile 14+0,12+0,9+0,6+0, or 3+0 axonemes 1/4, and the widespread non-motile metazoan 9+0 axonemes, are all derived through loss and modification from ancestral 9+2 organelles. 

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