Gene products specifying adhesion of uropathogenic Escherichia coli are minor components of pili.

The papE, papF, and papG genes of uropathogenic Escherichia coli are dispensable for the synthesis and assembly of pili associated with pyelonephritis, called Pap pili. Phenotypically, papF and papG mediate digalactoside [alpha-D-Galp-(1----4)-beta-D-Galp)-specific adhesion. Although whole bacterial cells of a papE mutant bind to this receptor, purified pili from such a mutant do not. This is in contrast to pili purified from the wild type, which bind specifically. The DNA sequences of the papE and papF genes are presented, together with the deduced primary structure of the gene products. Both proteins have most of the features characteristic of Escherichia coli type 1 and Pap pilins. The PapE protein can be detected in the purified wild-type pilus by NaDodSO4/polyacrylamide gel electrophoresis followed by silver staining or by autoradiography of gels to which radioiodinated pili have been applied. In rabbits immunized with purified Pap pili, antibodies specific for both PapE and PapF are produced. We propose that PapE and PapF are minor pilins in the Pap pilus.