The α anomer of mannose in the binding site of FimH. The mannose residue is buried in a unique site at the tip of the carbohydrate-recognition domain (left) in a deep and negatively charged pocket (right). FimH prefers to bind D-mannose in the α-anomeric configuration. The hydroxyl groups of D-mannose interact with residues Phe1, Asn46, Asp47, Asp54, Gln133, Asn135, Asp140, and Phe142 by hydrogen-bonding and hydrophobic interactions. Residues in direct contact are shown as a ball-and-stick model. W1, Water. (Redrawn, with permission, from Hung CS, et al. 2002. Mol Microbiol 44: 903–915, © John Wiley and Sons.)