FIGURE 2.

A, ribbon model representation of the newly determined Cma wt structure in a side view illustration (PDB 2XMX) is shown. The structure consists of three domains, the N-terminal translocation domain (in green; T), the intermediate receptor binding domain (blue; R), and the C-terminal activity domains (orange; R). The secondary structure elements and N (NT) and C termini (CT) of the structure as well as the two residues mutated are marked accordingly (α1-α5, β1-β6, NT, CT, P107, P176). B, superposition of the three structures represented as ribbon models (PDB 2XTR). The wt structure is color-coded in orange, the P107A mutant structure is in blue, and the P176A structure is in red. C, zoom into the region of the extended loop connecting the receptor binding and activity domain is shown. Wt and mutant structures are displayed in the same orientation and color-coded as in B, and adjacent residues of the mutant (P107A) are shown in ball-and-stick representation. D, close-up of the second mutation Pro-176 located in the β1-sheet of the protein is shown. wt and mutant structures are displayed in the same orientation and color coded as in B; adjacent residues of the P176A mutant are shown in a ball-and-stick representation.