Structure, Function and Biogenesis of Pili Formed by the Chaperone/Usher Pathway
Han Remaut and Gabriel Waksman
from: Pili and Flagella: Current Research and Future Trends (Edited by: Ken Jarrell). Caister Academic Press, U.K. (2009)
The chaperone/usher pathway is used by a wide range of gram-negative bacteria to expose adhesive filaments, called pili or fimbriae, on their outer surface. In pathogenic strains, pili constitute important virulence factors that allow host recognition and immune evasion via specific attachment, cell invasion and/or biofilm formation. Pilus biogenesis involves a periplasmic chaperone and an outer membrane protein called the usher. The periplasmic chaperone aids pilus subunit folding in the periplasm and maintains subunits in a polymerization-prone folding state. The usher recruits chaperone-subunit complexes to the outer membrane, facilitates their ordered polymerization and is responsible for pilus translocation to the outer surface. The tremendous advancements in the structural molecular characterization of pilus components and the chaperone/usher assembly machinery over the last two decades has brought the mechanistic understanding of this biosynthetic pathway to a point where strategies can now be developed for the targeted disarmament of bacteria of these virulence organelles read more ...