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Proc Natl Acad Sci U S A. 2002 Dec 10;99(25):16012-7. Epub 2002 Nov 22.

Single pilus motor forces exceed 100 pN.

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Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027, USA.

Erratum in

  • Proc Natl Acad Sci U S A. 2003 May 13;100(10):6287.


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.

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