Supporting Information

Files in this Data Supplement:

Fig. 6. Stereoimage of the 2fofc (blue) and fofc (red) omit electron density contoured around the PapD-bound pilicide 2c, at 1s and 3.5s respectively.

Fig. 7. Protein samples used in surface plasmon resonance assay. Lane 1, FimC-FimH; lane 2, FimD_N-His.

Fig. 8. FimC-FimH/FimD_N-His affinity determination. (A) Sample traces of surface plasmon resonance signal against time. Highest FimC-FimH concentration 800 nM, lowest 1.56 nM, with concentration halved at every step. (B) Plot of observed association rate constant k_obs against concentration of FimC-FimH.

Fig. 9. A model of pilicide action on chaperone-usher-mediated pilus assembly. The steps for native pilus assembly are shown in the left panel. In the first step, the nascent subunit peptide is secreted through the inner membrane where it is folded in the cleft of a cognate chaperone (1 and 2). Unfolded and free subunits in the periplasm are directed to degradation (A and B). The donor strand-complemented subunit-chaperone complexes are directed to the N terminus of the cognate usher (3) where it is bound first by the usher N terminus, followed by the C-terminal portion. The complex is uncapped, and a new incoming chaperone-subunit complex is directed to the usher where the incoming subunit interacts with the subunit docked at the usher to produce a growing series of subunits through and out of the usher pore (4). Free chaperone is released from the usher to be recycled and meet newly secreted peptides at the inner membrane (5 and 6). When pilicide is introduced into the periplasm from the extracellular media (Right), it is bound on the F1-G1 hydrophobic groove on chaperone engaged in a complex with pilus subunits (7). The pilicide bound to the chaperone-subunit complex interferes with the critical usher interaction (8), and the subsequent uncapping and incorporation of subunits into the pilus is inhibited (9, 10).

Table 1. Pilicides block P pilus assembly

*Representative HA-titers for duplicate runs.