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Molecular mechanism of P pilus termination in uropathogenic Escherichia coli

Denis Verger1, Eric Miller, Han Remaut

  • 1Institute of Structural Molecular Biology, University College London, Birkbeck College, Malet Street, London WC1E 7HX, UK.

EMBO Reports
|November 4, 2006
PubMed

Insights

P pili assembly relies on donor-strand exchange. A specialized subunit, PapH, terminates pilus growth by lacking the P5 pocket, preventing this crucial exchange mechanism.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • P pili are crucial adhesive fibers assembled via the chaperone-usher pathway.
  • Pilus assembly involves donor-strand exchange, where subunits integrate into the growing fiber.
  • This process is initiated at the P5 pocket through a zip-in-zip-out mechanism.

Purpose of the Study:

  • To elucidate the mechanism by which PapH terminates P pilus growth.
  • To investigate the structural basis for PapH's role in pilus assembly regulation.

Main Methods:

  • Structural analysis of the PapH subunit.
  • Comparison of PapH structure with other pilus subunits.
  • Investigating the interaction between PapH and the chaperone PapD.

Main Results:

  • PapH is incorporated at the pilus base and cannot undergo donor-strand exchange.
  • PapH lacks the critical P5 initiator pocket necessary for donor-strand exchange.
  • The PapD-PapH interaction strength does not account for the termination of exchange.

Conclusions:

  • PapH terminates P pilus growth by lacking the P5 pocket, thereby preventing donor-strand exchange initiation.
  • This structural deficiency in PapH is the key mechanism for halting pilus elongation.
  • Understanding this mechanism provides insights into the regulation of bacterial adhesion structures.

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