Identification of two ancillary subunits of Escherichia coli type 1 fimbriae by using antibodies against synthetic oligopeptides of fim gene products

Abstract

We have chemically synthesized oligopeptides corresponding to the NH2-terminal stretch of two gene products, designated FimG and FimH, of the fim gene cluster of Escherichia coli. These synthetic peptides, designated S-T1FimG(1-16) and S-T1FimH(1-25)C, evoked antibodies in rabbits that reacted with 14- and 29-kilodalton subunits, respectively, of dissociated fimbriae encoded by the recombinant plasmid pSH2 carrying the genetic information for the synthesis and expression of functional type 1 fimbriae. Neither of these fimbrial proteins was detected in dissociated fimbrial preparations from nonadhesive E. coli cells carrying the mutant plasmid pUT2002, containing a restriction site-specific deletion of fimG and fimH. Anti-S-T1FimH(1-25)C inhibited the adherence of type 1 fimbriated E. coli to epithelial cells. Immunoelectron microscopy revealed that anti-S-T1FimH(1-25)C, but not anti-S-T1FimG(1-16), bound to intact type 1 fimbriae of E. coli at the fimbrial tips and at long intervals along the fimbrial filaments. Anti-S-T1FimG(1-16) appeared to be directed at epitopes not accessible on the intact fimbriae and consequently failed to bind to intact fimbriae or to block fimbrial attachment. Our results suggest that the fimG and fimH gene products are components of type 1 fimbriae and that FimH may be the tip adhesin mediating the binding of type 1 fimbriated E. coli to D-mannose residues on mucosal surfaces.

Snapshots of usher-mediated protein secretion and ordered pilus assembly

“…2C, lanes 1 and 2). This result is consistent with previous results (30), and the hypothesis that the extreme N terminus of subunits is ''hidden'' in the multimerized structure because of ''head-to-tail'' interactions between subunits (22)(23)(24)31).…”

“…Thus, the oligomeric complex in the FimDCGH sample may consist primarily of a rod-like structure. It has been suggested previously that occasionally FimH can be intercalated within the type 1 pilus rod (30,34,35); the relative quantities of FimG and FimH in the FimDCGH assembly intermediate (Fig. 2 A, lane 2) suggest that there may be multiple FimH subunits in the multimer that is formed.…”

Localization of a domain in the FimH adhesin of Escherichia coli type 1 fimbriae capable of receptor recognition and use of a domain-specific antibody to confer protection against experimental urinary tract infection.

“…The FimA subunits constitute Ͼ 95% of the total fimbrial proteins and are arranged in a tight right-handed helix forming a central axial hole (20). Immune electron microscopy has revealed FimH to be placed strategically at the distal fimbrial tips and also, longitudinally, at various intervals (23,24). The FimH molecules that are localized at the fimbrial tips appear to be complexed with FimG, forming a flexible fibrillum structure (25).…”

Mast cell degranulation induced by type 1 fimbriated Escherichia coli in mice.

“…We have shown that type 1 fimbriae promote bacterial binding and activation of different immunoinflammatory cells such as lymphocytes and neutrophils, evoking a variety of biological reactions in the activated cells ( 14,15). The determinant of adherence and host cell activation on type 1 fimbriae is a minor protein, FimH, which is located in a functionally competent configuration at the tips of each fimbrial filament (16)(17)(18)(19).…”