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Single pilus motor forces exceed 100 pN

Berenike Maier1, Laura Potter, Magdalene So

  • 1Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027, USA.

Proceedings of the National Academy of Sciences of the United States of America
|November 26, 2002
PubMed

Insights

Neisseria gonorrhoeae uses single type IV pili fibers and one PilT complex for retraction force generation. This process, crucial for infection and DNA transfer, exhibits a high stall force, indicating efficient molecular motor function.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biophysics

Background:

  • Type IV pili retraction is essential for Neisseria gonorrhoeae infectivity and DNA transfer.
  • Understanding the single-molecule mechanics of pilus retraction is key to elucidating bacterial pathogenesis.

Purpose of the Study:

  • To investigate the roles of pilus number and the PilT motor in force generation during type IV pilus retraction.
  • To determine the single-molecule force characteristics and energetic requirements of pilus retraction.

Main Methods:

  • Single-molecule force measurements in vivo.
  • Analysis of retraction velocity and stall force under varying conditions.
  • Investigation of ATP-depletion effects on retraction dynamics.

Main Results:

  • Individual retraction events are powered by a single pilus fiber and a single PilT complex.
  • Retraction velocity is force-dependent, with a high average stall force of 110 +/- 30 pN.
  • ATP depletion reduces retraction rate but not stall force, suggesting multi-ATP involvement per subunit removal.

Conclusions:

  • The ATPase PilT likely functions as an oligomer to disassemble pili via cooperative conformational changes.
  • This mechanism provides significant force essential for Neisseria gonorrhoeae's biological functions.
  • The study offers insights into the molecular motor function driving bacterial motility and virulence.

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