Flagella/flagellin

Kuwajima, G., Kawagishi, I., Homma, M., Asaka, J.-I., Kondon, E., and Macnab, R. (1989). Export of an N-terminal fragment of Escherichia coli flagellin by a flagellum-specific pathway. Proc. Natl. Acad. Sd. U.S.A. 86, 4953—4957. 

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. 

Figure 34.29. Structure of Flagellin. A bacterial flagellum is a helical polymer of the protein flagellin. %...

The bacterial flagellum is a right-hand helical fiber, composed almost entirely of the fibrous protein flagellin. That is, the flagellum does not contain microtubules, actin, myosin (see here), or any contractile system. The flagellum itself rotates as a means of propelling the bacterium (Figure 8.29). 

Flagellin is a fibrous protein that composes most of the bacterial flagellum. 

Still imclear is how the protein synthesis that is taking place on the ribosomes in the bacterial cytoplasm is controlled and linked to "export machinery" at the base of the flagellin. As indicated in Fig. 19-3, the genetically identified proteins FlhA, FliH, and Flil are involved in the process that sends the correct flagellin subunits through the growing flagellum at the appropriate time. Flil contains an ATPase domain. FliS protein may be an export chaperone. ... 

The polymerization of flagellin to flagellum and that of tubulin to microtubule are also endothermic. The monomer-monomer bond free energy is of the same order as that in F-actin, although the dependency on the salt concentration is different in each. 

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