FIGURE 5.

Disorder in the nucleotide-binding domain (helix G) of the C_t-FDH E673Q mutant. A, schematic representation of dimer of subunits A and B of WT C_t-FDH (central panel, helices G are shown in yellow; NADP⁺ is shown in cyan) and stick representations of helices G in the apo- (left panel) and holo-E673Q (right panel). The 2|F_o| − |F_c| electron density maps (1 σ) are shown in blue. B, replacement of the active site glutamate with glutamine leads to disordering of helix G and an altered position of Arg-644. Schematic/stick representations of helix G and surrounding residues of the E673Q mutant in the absence (left) and presence (right) of NADP⁺ are shown. The red sphere represents a water molecule (see “Discussion” for details).