FIGURE 4.

C-terminal domain of MCD. A, stereo views of the superimposition of MCD (represented as described for Fig. 2 (A and B) in yellow and brown for the N-terminal (N-TER) and C-terminal (C-TER) domains, respectively) onto the GNAT-like domain of the polyketide synthase CurA (shown in blue). The GNAT folds of the two proteins superimpose with great accuracy despite a very low sequence identity. B, stereo view of the MCD and CurA active centers. The organization of residues that are considered to be essential for decarboxylase activity in CurA (Thr-355 and His-389 interacting with Tyr-419) remains mostly unchanged in MCD (Ser-329 and His-423 interacting with Tyr-456). The molecule of malonyl-CoA found in the complex with CurA (Protein Data Bank code 2REF) suggests that, in MCD, the binding site for the cofactor might require some adjustments only for the base moiety.