Pilus chaperone FimC-adhesin FimH interactions mapped by TROSY-NMR

The 23 kDa two-domain periplasmic chaperone FimC from Escherichia coli is r equired for the assembly of type-1 pili, which are filamentous, highly olig omeric protein complexes anchored to the outer bacterial membrane that medi ate adhesion of pathogenic E. coli strains to host cell surfaces. Here we i dentified the contact sites on the surface of the NMR structure of FimC tha t are responsible for the binding of the 28 kDa mannose-binding type-1 pilu s subunit FimH by N-15 and H-1 NMR chemical shift mapping, using transverse relaxation-optimized spectroscopy (TROSY). The FimH-binding surface of Fim C is formed nearly entirely by the N-terminal domain, and its extent and sh ape indicate that FimC binds a folded form of the pilus subunits.