Bacterial FimH adhesin (FimH)

The bacterial FimH adhesin is a two-domain, mannose-specific lectin located at the tip of type 1 fimbriae (pili) of Gram-negative enterobacteria, especially *Escherichia coli*. The N-terminal lectin domain mediates high-affinity binding to terminal mannose residues on host cell surface glycoproteins, facilitating bacterial adherence to epithelial cells and colonization, especially in the urinary tract. The C-terminal pilin domain anchors FimH to the fimbrial organelle and modulates its allosteric state and adhesive properties. FimH is essential to the pathogenesis of urinary tract and other infections by enabling bacteria to resist mechanical washout and establish persistent infections. Its adhesion employs a catch-bond mechanism, where ligand affinity increases under shear force, enabling robust host attachment during urine flow. This functional significance makes FimH a prominent antibacterial drug and vaccine target: small molecule mannosides and monoclonal antibodies have been designed to block its function. Numerous FimH structural variants exist among different bacterial strains, impacting tissue tropism and virulence.

Other names

FimHType 1 fimbrial adhesinType 1 pilus adhesinMannose-specific adhesin

Inhibition of mannose-binding to block bacterial adhesion; Competitive inhibition at carbohydrate-binding site; Antibody-mediated conformational trapping; Allosteric inhibition to prevent catch-bond formation