FIGURE 2.

Close-up of regions and residues selected to explore the allosteric pathway between the low and high affinity structures of the lectin domain of FimH. A, two states of the pocket zipper show the backbone hydrogen bonding (dashed lines) and residue Ala-10, which was selected for mutagenesis. B, shown are both conformations for the sequential stretch of 13 amino acids encompassing the β-bulge (purple) and α-switch (gold). Highlighted amino acids selected for mutagenesis to bias FimH toward one conformational state are shown as sticks. The two side chain conformations for Arg-60 shown in the low affinity structure reflect the 50/50 occupancy status observed in the crystal structure. C, shown is spatial orientation of selected residues from the interdomain loops. All residues shown interact with different neighbors when they shift between the low and high affinity structures, with many residues switching from being buried to solvent-exposed.