title: Single pilus motor forces exceed 100 pN.
abstract: Force production by type IV pilus retraction is critical for infectivity of Neisseria gonorrhoeae and DNA transfer. We investigated the roles of pilus number and the retraction motor, PilT, in force generation in vivo at the single-molecule level and found that individual retraction events are generated by a single pilus fiber, and only one PilT complex powers retraction. Retraction velocity is constant at low forces but decreases at forces greater than 40 pN, giving a remarkably high average stall force of 110 +/- 30 pN. Further insights into the molecular mechanism of force generation are gained from the effect of ATP-depletion, which reduces the rate of retraction but not the stall force. Energetic considerations suggest that more than one ATP is involved in the removal of a single pilin subunit from a pilus. The results are most consistent with a model in which the ATPase PilT forms an oligomer that disassembles the pilus by a cooperative conformational change.
authors.affiliation: Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027, USA.
authors.forename: Berenike
authors.initials: B
authors.lastname: Maier
authors.forename: Laura
authors.initials: L
authors.lastname: Potter
authors.forename: Magdalene
authors.initials: M
authors.lastname: So
authors.forename: Cynthia D
authors.initials: CD
authors.lastname: Long
authors.forename: Hank S
authors.initials: HS
authors.lastname: Seifert
authors.forename: Michael P
authors.initials: MP
authors.lastname: Sheetz
mesh_terms: D000251:Adenosine Triphosphatases / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins; D001696:Biomechanical Phenomena; D010861:Fimbriae, Bacterial / Q000502:physiology*; D007700:Kinetics; D008854:Microscopy, Electron; D020409:Molecular Motor Proteins / Q000502:physiology*; D009068:Movement; D009344:Neisseria gonorrhoeae / Q000502:physiology / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D020409:Molecular Motor Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases