Root-mean-square deviations from the apo structure of B. pseudomallei GCDH for (a) main-chain and (b) side-chain atomic coordinates of human GCDH as well as fragment-bound structures of BpGCDH near the catalytic active site. (a) The backbone residues of the human GCDH–FAD–NBC ternary complex are structurally similar to those of apo BpGCDH. Binding small molecules causes backbone conformational changes which deviate from the apo BpGCDH structure. (b) The side-chain deviations between the apo bacterial structure and the human ternary complex tend to be smaller than those observed between apo and fragment-bound structures of BpGCDH. PDB codes are listed in the legend and the structures of all four GCDH-binding fragments are shown at the top. The alignment was performed using the SSM superposition function from the CCP4 program suite (Krissinel & Henrick, 2004; Winn et al., 2011).