FIGURE 5.

Loop-3 dihedral angles of drug-free and TPP⁺-bound EmrE. A and B, the chemical shift index (observed - random coil) for CA indicates a β-strand structure in loop-3 for both drug-free EmrE (A) and TPP⁺-bound EmrE (B) (69, 70). C and D, using the backbone chemical shifts of loop-3, the dihedral angles of this loop were calculated using TALOS+ (62) for both drug-free EmrE (C) and TPP⁺-bound EmrE (D). Residues 81 through 84 have dihedral angles characteristic of β-strand. E and F, random coil index-predicted order parameters, S², for loop-3 show that the loop is relatively ordered in both the drug-free (E) and the TPP⁺-bound (F) states (63, 64).