Figure 7.

Schematic overview of the conformational changes of FimH (I). FimH crystal structures, which correspond to each individual state are shown in boxes. In the absence of urine flow FimH is in the low-affinity conformation, characterized by an open binding pocket and intertwined domains (A, PDB: 4XOD). Upon ligand binding, FimH adopts the medium-affinity conformation (B, PDB: 4XOE), in which a loop (highlighted in green in the crystal structures) closes in the ligand, forming a deep and well-defined binding pocket. As urine begins to flow, the two domains are pulled apart, inducing the high-affinity conformation (C, PDB: 4XOB). LD, lectin domain; PD, pilin domain [72].