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

Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, Brussels, Belgium.
Acta Crystallographica Section D Biological Crystallography (Impact Factor: 2.67). 06/2009; 65(Pt 5):411-20. DOI: 10.1107/S0907444909005174
Source: PubMed


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 previously 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.

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Available from: Julie Bouckaert, Aug 30, 2014
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    • "The first structure of periplasmic assembly chaperone (PapD) was solved in 1989 (Holmgren & Branden, 1989). Later on, several other periplasmic chaperone structures have been determined (Van Molle et al., 2009; Remaut et al., 2006; Knight et al., 2002; Choudhury et al., 1999; Pellecchia et al., 1998). The structures revealed two immunoglobulin-like domains joined together at an approximate 90° angle, with a large cleft between these two domains. "

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    • "FaeE crystal structure shows a dimer formed by an interaction between pilin-binding interfaces of two monomers. Thermodynamic and biochemical data show that FaeE occurs as a stable monomer in solution (Van Molle et al., 2009). "
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