Fadel A. Samatey
from: Pili and Flagella: Current Research and Future Trends (Edited by: Ken Jarrell). Caister Academic Press, U.K. (2009)
Since its discovery, the flagellum has fascinated researchers. The scientific community had been wondering about the composition, the construction and the function, at the molecular level, of such an organelle. All available techniques in genetics, molecular biology, electron microscopy, X-ray diffraction, electron cryotomography and molecular dynamics simulation have been used, quite successfully, independently or in a combined manner to answer many of the questions. It is now well established that the flagellum is a complex multi-component organelle that spans from the cell membrane to outside of the cell, with the exception of the spirochete flagellum that stays in the periplasmic space. The flagellum self-assembles to form a helical propeller that enables prokaryotic cells to swim in its living environment. Diverse structural studies are done to understand the molecular interactions relative to its function. The nature of the flagellum makes it suitable for structural studies using electron microscopy and three-dimensional image reconstruction techniques. Therefore, electron microscopy has given many structural models of flagella from different species of Archaea and Bacteria. Structural investigations of flagellar systems have been more successful by combining X-ray diffraction and electron microscopy. The combination of these techniques produced high-resolution models of the filament from S. typhimurium read more ...