Bacteria flagella

Among subcellular proteomes investigated for identification of bacterial subspecies, attention was concentrated on surface and membrane-associated proteins, especially outer membrane proteins (OMPs) of Gram-negative bacteria, surface layer (S-layer) proteins of Gram-positive bacteria, flagella, and extracellular proteins (ECPs). 

Flagella are threads of protein often 2fim. long which start as small basal organs just beneath the cytoplasmic membrane. They are responsible for the movement of motile bacteria. Their number and distribution varies. Some species bear a single flagellum, others are flagellate over their whole surface. 

The number and arrangement of flagella vary with different bacteria, but they are generally constant for each species. Some have only one flagellum others have two or more flagella. 

Bacteria may have the shape of spheres or straight or curved rods. Some, such as the actmomycetes, grow in a branching filamentous form. Words used to describe bacteria often refer to these shapes a coccus is a sphere, a bacillus a rod, and a vibrio a curved rod with a flagellum at one end. A spirillum is screwshaped. These same words are frequently used to name particular genera or families. Other names are derived from some chemical activity of the bacterium being described. 

Such behavior raised many questions. What causes reversal of direction of the propellor Why do the bacteria tumble How does a bacterium "decide" when to tumble How is the flagellum changed from a left-handed to a right-handed superhelix How does this behavior help the bacterium to find food Most intriguing of all, what kind of motor powers the... 

Another form of displayed peptide library is the FliTrx Random Peptide Display Library (Invitrogen, Paisley, UK), which uses the bacterial flagellum to display random peptide libraries on the E. coli cell surface (14). This library was constructed in the pFliTrx vector, which positions the random peptides in a flagellin (Fli) thioredoxin (Trx) fusion protein. Biopanning with bacteria works surprisingly well in our experience (15) and screening on nitrocellulose is similar to the Smith method. 

Some bacteria boast a marvelous swimming device, the flagellum, which has no counterpart in more complex cells.8 In 1973 it was discovered that some bacteria swim by rotating their flagella. So the bacterial flagellum acts as a rotary propeller—in contrast to the cilium, which acts more like an oar. 

FlhB A component of the flagellum-specific export apparatus in bacteria... 

When Walker was a postdoc, people argued whether this was rotation, or whether it was beating in a sinusoidal fashion. The key experiment was that somebody made an antibody that recognized the end of the flagellum and they took a cover slip and coated it with the antibody and added the bacteria to it. This then trapped the bacteria attached by the tip of their tail, and one could look in the fight microscope and see the bacteria turning around in this fashion. This was the first demonstration of rotation in these motile bacteria. The ATP experiment mentioned above was a derivative from this bacteria motility experiment, a macroscopic demonstration of a microscopic chemical event. 

Flagella - Flagella (singular, flagellum) are hairlike structures that provide a means of locomotion for those bacteria that have them. They can be found at either or both ends of a bacterium or all over its surface. The flagella beat in a propeller-like motion to help the bacterium move toward nutrients away from toxic chemicals or, in the case of the photosynthetic cyanobacteria toward the light. 

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