The Bacterial Flagellum as a Surface Display and Expression Tool
Katariina Majander, Lena Anton, Riikka Kylväjä, and Benita Westerlund-Wikström
from: Pili and Flagella: Current Research and Future Trends (Edited by: Ken Jarrell). Caister Academic Press, U.K. (2009)
The complex and self-assembling bacterial flagellum was earlier considered solely as a motility organelle used by bacteria and archaea for swimming towards attractants. In recent years, additional functions for the flagellum have been reported, such as adhesive properties, involvement in biofilm formation, sensor of environmental wetness, and importantly, a molecule recognized by components of the innate immune system of eukaryotic cells. This review will summarize the basis and use of the flagellum in bacterial surface display, as an apparatus for extracellular secretion, as a vaccine component, and in expression techniques. Targeting of foreign polypeptides to the bacterial surface is based on fusion by genetic methods of the heterologous polypeptide to a surface-localized carrier protein. Subunits of the flagellum, i.e. the major subunit FliC and the tip-localized FliD, can be used for surface display of foreign polypeptides in e.g. basic research, construction of random peptide libraries, vaccinology, and for diagnostic purposes. Surface-localized flagellar subunits are translocated to the extracellular milieu by the flagellar secretion apparatus, which can be utilized for high-yield export of foreign polypeptides into the bacterial growth medium. The flagellar subunit is, due to its potency as an immunomodulator, being explored as a carrier of antigens in vaccine design read more ...