Fig. 1.

Schematic view of P-pili. P-pili are helical fibers extending from the outer membrane of pyelonephritic E. coli. The adhesin, PapG, binds to uroepithelial cells on its human host and is the most distal protein of the pilus fiber. PapG is followed by an adaptor protein, PapF, multiple copies of a fibrillar protein, PapE, an adaptor protein, PapK, and ≈1,000 copies of the major structural pilin, PapA. The pilus is anchored into the membrane by PapH (data not shown). All of the pilin subunits exit the cell during pilus assembly by passing through the usher, PapC, which is inserted in the outer membrane (OM) (see review in ref. 4). This figure was adapted from ref. 25.