Conservation of the D-mannose-adhesion protein among type 1 fimbriated members of the family Enterobacteriaceae

Abstract

A variety of genera and species of the family Enterobacteriaceae bear surface fimbriae that enable them to bind to D-mannose residues on eukaryotic cells^1–3. Until recently, it was thought that the D-mannose binding site was located in the major structural subunit (FimA), of relative molecular mass (M_r) 17,000 (17 K), of these organelles in Escherichia coli^4,5. New evidence indicates that this binding site resides instead in a minor protein M_r 28–31 K (FimH) located at the tips and at long intervals along the length of the fimbriae^6–12, and is reminiscent of the minor tip adhesion proteins of pyelonephritis-associated pili (Pap) and S fimbriae^13,14. In contrast to the antigenic heterogeneity of the major FimA subunit, the antigenic structure of FimH is conserved among different strains of E. coli^10,11. Here, we report an even broader conservation of this minor adhesion protein extending to other genera and species of type 1 fimbriated Enterobacteriaceae. Our results may have implications for the development of broadly protective vaccines against Gram-negative bacillary infections in animals and perhaps in man.