Chaperone priming of pilus subunits facilitates a topological transition that drives fiber formation

Cell. 2002 Nov 15;111(4):543-51. doi: 10.1016/s0092-8674(02)01050-4.


Periplasmic chaperones direct the assembly of adhesive, multi-subunit pilus fibers that play critical roles in bacterial pathogenesis. Pilus assembly occurs via a donor strand exchange mechanism in which the N-terminal extension of one subunit replaces the chaperone G(1) strand that transiently occupies a groove in the neighboring subunit. Here, we show that the chaperone primes the subunit for assembly by holding the groove in an open, activated conformation. During donor strand exchange, the subunit undergoes a topological transition that triggers the closure of the groove and seals the N-terminal extension in place. It is this topological transition, made possible only by the priming action of the chaperone that drives subunit assembly into the fiber.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Fimbriae, Bacterial* / metabolism
  • Membrane Proteins*
  • Models, Molecular
  • Molecular Chaperones / chemistry*
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism
  • Periplasmic Proteins / chemistry*
  • Periplasmic Proteins / genetics
  • Periplasmic Proteins / metabolism
  • Protein Structure, Tertiary
  • Proton-Translocating ATPases*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism


  • Bacterial Proteins
  • Escherichia coli Proteins
  • Membrane Proteins
  • Molecular Chaperones
  • PapD protein, E coli
  • PapK protein, bacteria
  • Periplasmic Proteins
  • Recombinant Fusion Proteins
  • Proton-Translocating ATPases
  • AtpH protein, E coli

Associated data

  • PDB/1N1Z
  • PDB/1NOL