Search results
Results from the WOW.Com Content Network
A pilus (Latin for 'hair'; pl.: pili) is a hair-like cell-surface appendage found on many bacteria and archaea. [1] The terms pilus and fimbria (Latin for 'fringe'; plural: fimbriae) can be used interchangeably, although some researchers reserve the term pilus for the appendage required for bacterial conjugation.
P fimbriae are large, linear structures projecting from the surface of the bacterial cell. With lengths of 1-2um, the pili can be larger than the diameter of the bacteria itself. [ 4 ] The main body of the fimbriae is composed of approx. 1000 copies of the major fimbrial subunit protein PapA, forming a helical rod. [ 5 ]
The Saf pilin N-terminal extension protein domain helps the pili to form, via a complex mechanism named the chaperone/usher pathway. It is found in all c-u pilins. [8] This protein domain is very important for such bacteria, as without pili formation, they could not infect the host. Saf is a Salmonella operon containing a c-u pilus system. [8]
Fimbriae are believed to be involved in attachment to solid surfaces or to other cells, and are essential for the virulence of some bacterial pathogens. [86] Pili ( sing . pilus) are cellular appendages, slightly larger than fimbriae, that can transfer genetic material between bacterial cells in a process called conjugation where they are ...
Pili retraction produces pulling forces on the bacterium, which will be pulled in the direction of the vector sum of the pili forces, resulting in a jerky movement. A typical type IV pilus can produce a force exceeding 100 piconewtons [ 79 ] and then a bundle of pili can produce pulling forces up to several nanonewtons . [ 80 ]
Sequence comparison indicates that the archaeal flagellum is homologous to bacterial Type IV pili, filamentous structures outside the cell. [11] Pilus retraction provides enables a different form of bacterial motility called "twitching" or "social gliding" which allows bacterial cells to crawl along a surface, They are assembled through the ...
Gliding motility is a type of translocation used by microorganisms that is independent of propulsive structures such as flagella, pili, and fimbriae. [1] Gliding allows microorganisms to travel along the surface of low aqueous films. The mechanisms of this motility are only partially known.
Twitching motility is a form of crawling bacterial motility used to move over surfaces. Twitching is mediated by the activity of hair-like filaments called type IV pili which extend from the cell's exterior, bind to surrounding solid substrates, and retract, pulling the cell forwards in a manner similar to the action of a grappling hook.