Isolation and characterization of the alpha-galactosyl-1,4-beta-galactosyl-specific adhesin (P adhesin) from fimbriated Escherichia coli.

The alpha-galactosyl-1,4-beta-galactosyl-specific adhesin (P adhesin) was isolated from the fimbria-adhesin complex (FAC) of recombinant Escherichia coli strains expressing the F7(1), F8, or F13 fimbrial antigens. Separation into fimbriae and adhesin was achieved by heating the FAC to 80 degrees C in the presence of Zwittergent 3-16. After removal of the fimbriae by precipitation with lithium chloride, the adhesin was purified by anion-exchange fast protein liquid chromatography in the presence of 4 M urea. The purified adhesins from the three strains had pIs of 4.8 to 5.0 and molecular weights of approximately 35,000. The fimbrillins were smaller, their molecular weights being different with different F antigens. The amino-terminal amino acid sequence of the F7(1)- and F13-derived adhesins were different, that of the F13-derived adhesin being identical to that extrapolated from the DNA sequence of the papG gene (B. Lund, G. Lindberg, B.-I. Marklund, and S. Normark, Proc. Natl. Acad. Sci. USA 84:5898-5902). An antiadhesive monoclonal antibody which reacted with the three P adhesins was prepared. The FAC and the purified adhesins but not the fimbriae from which the adhesins had been removed agglutinated erythrocytes and galactose-galactose-coated latex beads. The adhesion of erythrocytes to the surface-fixed adhesins could be specifically inhibited with alpha-galactosyl-1,4-beta-galactosyl-1,4-glucosyl. The results indicate that the P adhesin(s) of uropathogenic E. coli represents a group of related proteins with conserved receptor recognition domains. The F13-derived P adhesin is the PapG protein postulated by Normark and his colleagues (Lund et al., Proc. Natl. Acad. Sci. USA 84:5898-5902; B. Lund, F. Lindberg, and S. Normark, J. Bacteriol. 170:1887-1894).