Four G adhesins, cloned from uropathogenic Escherichia coli strains, were examined for binding to glycolipids and various eukaryotic cells. PapGAD110 and PapGIA2 showed virtually identical binding patterns to Gal alpha 1‐4Gal‐containing glycolipids, while PapGJ96 differed slightly and PrsGJ96 markedly with respect to the effect of neighbouring groups on the binding. Their hemagglutination patterns confirmed the existence of three receptor‐binding specificities. While the PapG adhesins bound to uroepithelial cells from man (T24) but not to those from the dog (MDCK II), the reverse was true of PrsG. These binding patterns were largely explained by the absence or presence of appropriate glycolipid isoreceptors, although the inability of the PapG adhesins to bind MDCK II cells was attributed to an inappropriate presentation of their receptor epitopes. The high prevalence of PrsG‐like specificities observed among wild‐type dog uropathogenic E. coli isolates, together with the determined isoreceptor composition of human and dog kidney target tissues, suggest variation in receptor specificity as a mechanism for shifting host specificity, and that this variation has evolved in response to the topography of the host cellular receptors. The receptor‐binding half proposed for the predicted amino acid sequences of the four G adhesins and the corresponding adhesin of one of the dog E. coli isolates varied considerably among the three receptor‐binding groups of adhesins, but only little within each group.

No abstract

Strains of the bacterium Escherichia coli that cause infections of the human urinary tract produce so-called Pap-pili, which are hair-like appendages consisting of about 10(3) helically arranged subunits of the protein PapA. These pili mediate binding to digalactoside-containing glycolipids present on the epithelial cells which line the urinary tract. Recently, it has been suggested that three proteins, PapE, PapF and PapG, are responsible for this binding. In the absence of PapA, non-piliated bacteria are formed which nonetheless exhibit binding, showing that the bulk of the pilus is not essential for binding. Although pili can form without PapF and PapG, such pili are unable to bind to the digalactoside. The protein PapG mediates binding specificity in trans-complementation experiments, so this protein is the digalactoside-specific adhesin. Using immuno-electron microscopy we have found that Pap-pili are heteropolymers composed of the major pilin, PapA, the minor pilins, PapE and PapF, and the adhesin, PapG. The last three proteins are located at the tip of the pilus.

Uropathogenic Escherichia coli adhere to uroepithelial cells by their digalactoside a-D-galactopyranosyl-

Most pyelonephritic Escherichia coli strains bind to digalactoside‐containing glycolipids on uroepithelial cells. Purified Pap pili (pili associated with pyelonephritis) show the same binding specificity. A non‐polar mutation early in the papA pilin gene abolishes formation of Pap pili but does not affect the degree of digalactoside‐specific hemagglutination. Three novel pap genes, papE, papF and papG are defined in this report. The papF and papG gene products are both required for digalactoside‐specific agglutination by whole bacteria cells as well as for agglutination by pilus preparations. Pili prepared from a papE mutant have lost their binding ability although whole cells from this mutant retain it, implying an adhesin anchoring role for the papE gene product. A mutant with lesions both in the papA and the papE genes does not mediate digalactoside‐specific agglutination. The implications of this finding for pilus biogenesis are discussed.