X-ray structure of the FimC-FimH chaperone-adhesin complex from uropathogenic Escherichia coli

Type 1 pili-adhesive fibers expressed in most members of the Enterobacteria ceae family-mediate binding to mannose receptors on host cells through the FimH adhesin. Pilus biogenesis proceeds by way of the chaperone/usher pathw ay. The x-ray structure of the FimC-FimH chaperone-adhesin complex from uro pathogenic Escherichia coli at 2.5 angstrom resolution reveals the basis fo r carbohydrate recognition and for pilus assembly. The carboxyl-terminal pi lin domain of FimH has an immunoglobulin-like fold, except that the seventh strand is missing, leaving part of the hydrophobic core exposed. A donor s trand complementation mechanism in which the chaperone donates a strand to complete the pilin domain explains the basis for both chaperone function an d pilus biogenesis.