Archaeal Flagella and Pili
Ken F. Jarrell, David J. VanDyke and John Wu
from: Pili and Flagella: Current Research and Future Trends (Edited by: Ken Jarrell). Caister Academic Press, U.K. (2009)
Archaeal flagella and pili are unique cellular appendages that are distinct from their bacterial namesakes. The better studied of the two structures is the archaeal flagellum. While it resembles the bacterial flagellum in terms of being a reversible rotating organelle responsible for swimming motility, its composition, structure and likely mode of assembly are all very different. Archaeal flagella have a unique structure which lacks a central channel. Similar to bacterial type IV pilins, the component flagellins are made with class 3 signal peptides and they are processed by a type IV prepilin peptidase-like enzyme. The flagellins are typically modified by the addition of N-linked glycans which are necessary for proper assembly and/or function. The study of archaeal pili is extremely limited. In Methanococcus maripaludis, the structures are formed from type IV pilin-like proteins, again possessing class 3 signal peptides processed by a type IV prepilin peptidase-like enzyme. However, the structure of the assembled pilus does not resemble any known bacterial pilus type and, unlike type IV pili, has a central channel of a diameter similar to that observed in bacterial flagella read more ...