The F4 fimbrial chaperone FaeE is stable as a monomer that does not require self-capping of its pilin-interactive surfaces

Inge Van Molle, Kristof Moonens, Lieven Buts, Abel Garcia-Pino, Santosh Panjikar, Lode Wyns, Henri De Greve, Julie Bouckaert

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5 Citations (Scopus)


Many Gram-negative bacteria use the chaperone-usher pathway to express adhesive surface structures, such as fimbriae, in order to mediate attachment to host cells. Periplasmic chaperones are required to shuttle fimbrial subunits or pilins through the periplasmic space in an assembly-competent form. The chaperones cap the hydrophobic surface of the pilins through a donor-strand complementation mechanism. FaeE is the periplasmic chaperone required for the assembly of the F4 fimbriae of enterotoxigenic Escherichia coli. The FaeE crystal structure shows a dimer formed by interaction between the pilin-binding interfaces of the two monomers. Dimerization and tetramerization have been observed pre-viously in crystal structures of fimbrial chaperones and have been suggested to serve as a self-capping mechanism that protects the pilin-interactive surfaces in solution in the absence of the pilins. However, thermodynamic and biochemical data show that FaeE occurs as a stable monomer in solution. Other lines of evidence indicate that self-capping of the pilin-interactive interfaces is not a mechanism that is conservedly applied by all periplasmic chaperones, but is rather a case-specific solution to cap aggregation-prone surfaces.

Original languageEnglish
Pages (from-to)411-420
Number of pages10
JournalActa Crystallographica Section D: Biological Crystallography
Issue number5
Publication statusPublished - 18 Apr 2009
Externally publishedYes


  • Chaperone-usher pathway
  • Fimbriae
  • Periplasmic chaperones
  • Self-capping

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