Figure 7.

Conformational exchange in the RslTpt1 C-lobe when bound to NAD⁺. (A) Exchange contributions [R_ex = > 5 s⁻¹] to the multiple-quantum relaxation rates of Ile (δ1), Leu, Val and Met methyl resonances for apo-RslTpt1 (black) and the RslTpt1·NAD⁺ complex (red) are plotted against residue number. Those residues that display the largest R_ex values for the apo (Ile109: 33.6 s⁻¹ and Ile114: 18.2 s⁻¹) and the NAD⁺-bound states (Val124: 27.8 s⁻¹ and Val165: 16.6/12.1 s⁻¹) are labeled. (B) The R_ex values of methyl groups (denoted by spheres) are mapped onto the structure of the C-lobe in its NAD⁺-bound state and shown using a blue to red gradient; methyl groups without any detectable R_ex values are colored gray. Leu124 that shows the largest exchange contribution in the bound state lies in close spatial proximity to the phosphate backbone; Val165, whose methyl groups display substantial R_ex values contact the nicotinamide moiety. Also indicated (in black font) are Ile109 and Ile114 that show substantial R_ex values in the unliganded state. These residues, that engage the adenosine moiety of NAD⁺, have no detectable exchange contributions in the NAD⁺-bound state.