Species name： Pseudomonas aeruginosa
Harvard UniversityDepartment of Molecular and Cellular BiologyHarvard Biological Labs Howard C. Berg
Using optical tweezers, Mertz et al. (2000) demonstrated that Type IV pili could retract with considerable force (> 80 pN). Mutants that were pili-less or had non-retractile pili were non-motile; thus pilus retraction powers twitching motility. The pili were not observed directly -- pilus function was assayed by monitoring the position of a latex bead attached to pili with antibodies. We developed a technique to label pili using an amino-reactive Cy3 and observed directly pilus extension, pilus retraction, and retraction-mediated cell movement (Skerker & Berg, 2000).
Mertz, A.J., So, M. and Sheetz, M.P. Pilus retraction powers bacterial twitching motility. Nature 407, 98-102 (2000).
Skerker, J.M. and Berg, H.C. Direct observation of extension and retraction of type IV pili. Proc Natl. Acad. Sci. USA, 98, 6901-6904 (2001).
(2014.03.20)