ROLES OF THE PAP-ENCODED AND PRS-ENCODED ADHESINS IN ESCHERICHIA-COLI ADHERENCE TO HUMAN UROEPITHELIAL CELLS

In this study, we reexamined the structural prerequisites for the attachment of P-fimbriated Escherichia coli to human urinary tract epithelial cells. The epithelial cells were obtained from A1P1 nonsecretor individuals, who express the globoseries of glycolipids without the ABH blood group determinants, and from A1P1 secretor individuals, who in addition express globo-A, a receptor for the prs(J96) adhesin. The wild-type E. coli strains J96, AD110, and IA2 and the recombinant clones HB101 pap(J96), HB101 prs(J96), HB101 pap(IA2), and HB101 pap(AD110) were tested for binding. They expressed P fimbriae, as defined by P blood group-dependent agglutination of human erythrocytes of the globoseries, but differed in reactivity with galactose-alpha-1-4galactose-beta (Gal-alpha-1-4Gal-beta)-latex beads, isolated glycolipids of the globoseries, sheep erythrocytes, and uroepithelial cells. Three different patterns of binding were represented among the recombinant clones. HB101 pap(IA2) and HB101 pap(AD110) agglutinated sheep erythrocytes and Gal-alpha-1-4Gal-beta-latex beads and attached to both secretor and nonsecretor epithelial cells. HB101 prs(J96) agglutinated sheep erythrocytes, reacted poorly with Gal-alpha-1-4Gal-beta-latex beads, and attached to A1 secretor but not to A1 nonsecretor epithelial cells. HB101 pap(J96) agglutinated Gal-alpha-1-4Gal-beta-latex beads but not sheep erythrocytes and attached poorly to human uroepithelial cells. The receptors relevant for adhesion were analyzed by inhibition with glycolipids in suspension. The sheep erythrocyte agglutination and attachment to secretor and nonsecretor epithelial cells of HB101 pap(IA2) and HB101 pap(AD110) were inhibited by globotetraosylceramide, while the Forssman glycolipid had no effect. The sheep erythrocyte reactivity and attachment to secretor epithelial cells of HB101 prs(J96) were inhibited by the Forssman glycolipid. These results permitted three conclusions. First, the expression of functionally active Gal-alpha-1-4Gal-beta-specific adhesins, as in HB101 pap(J96), was not sufficient to make E. coli competent to attach to human uroepithelial cells. Attachment required P fimbriae of the pap(IA2) or pap(AD110) type. Second, the sheep erythrocyte reactivity of P-fimbriated strains could not be attributed solely to recognition of the Forssman glycolipid and may not be used to define the prs(J96)-encoded phenotype. Third, the P-fimbrial adhesins which mediate secretor state-independent attachment to human uroepithelial cells recognized receptor epitopes provided by globotetraosylceramide.