title: Dynamics of type IV pili is controlled by switching between multiple states.
abstract: Type IV pili are major bacterial virulence factors supporting adhesion, surface motility, and gene transfer. The polymeric pilus fiber is a highly dynamic molecular machine that switches between elongation and retraction. We used laser tweezers to investigate the dynamics of individual pili of Neisseria gonorrheae at clamped forces between 8 pN and 100 pN and at varying concentration of the retraction ATPase PilT. The elongation probability of individual pili increased with increasing mechanical force. Directional switching occurred on two distinct timescales, and regular stepping was absent on a scale > 3 nm. We found that the retraction velocity is bimodal and that the bimodality depends on force and on the concentration of PilT proteins. We conclude that the pilus motor is a multistate system with at least one polymerization mode and two depolymerization modes with the dynamics fine-tuned by force and PilT concentration.
authors.affiliation: Institut für Allgemeine Zoologie und Genetik, Westfälische Wilhelms Universität, 48149 Münster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Clausen
authors.forename: Michael
authors.initials: M
authors.lastname: Koomey
authors.forename: Berenike
authors.initials: B
authors.lastname: Maier
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D001696:Biomechanical Phenomena; D010861:Fimbriae, Bacterial / Q000737:chemistry* / Q000378:metabolism*; D009068:Movement; D009344:Neisseria gonorrhoeae / Q000166:cytology*; D011336:Probability; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D000251:Adenosine Triphosphatases