Escherichia coli type 1 fimbrial D-mannose-specific adhesin (FimH) (FimH)

The Escherichia coli type 1 fimbrial D-mannose-specific adhesin (FimH) is a highly conserved protein located at the tip of type 1 pili/fimbriae on the surface of E. coli. It mediates bacterial adhesion by specifically recognizing and binding terminally exposed mannose residues on glycoproteins present on host cell surfaces—a critical step for colonization during infection such as urinary tract infections. Structurally, mature FimH consists of two domains: an N-terminal lectin domain responsible for mannose binding and a C-terminal pilin domain that anchors it into the pilus structure; these domains are connected via a short linker region. The lectin domain contains a β-barrel-shaped pocket that confers high affinity for mannose through hydrophilic interactions inside the pocket and hydrophobic guidance at its entrance. The function of FimH is allosterically regulated—mechanical forces encountered during flow conditions can enhance its adhesive strength (“catch bond” behavior), which is important for bacterial persistence under physiological shear stress conditions such as those found in urine flow within the urinary tract. This makes it an attractive target both for drug development aimed at preventing/treating infections without antibiotics and as a model system for studying mechanoregulation in biological adhesion systems.

Other names

Type 1 fimbrial adhesinType 1 fimbrin D-mannose specific adhesinProtein FimHb4320 (gene locus)JW4283 (gene locus)

Drugs or inhibitors targeting this molecule typically act by blocking the mannose-binding pocket on FimH, thereby preventing E. coli from adhering to host tissues and establishing infection