FIGURE 5.

Hypothetical model for T. brucei AdoMetDC activation. A, WT, wild-type AdoMetDC ±putrescine (Put) showing that binding to putrescine leads to partial activation, whereas formation of the heterodimer with prozyme leads to full activation. The N terminus is shown undergoing a hypothetical conformational change as part of the activation process. B, LSL to Ala triple mutant; MAM to Ala double mutant, and the Δ16 truncation mutant ±putrescine showing that the heterodimeric enzymes exist in a low activity conformation(s), although binding to putrescine leads to partial activation of some of the mutants. Multiple low activity and partially active conformations may be present; thus, not all low activity or partially active forms may be structurally equivalent.