Figure 6.

Three-dimensional structural models of the autotransporter protein IcsA. Protein secondary structure is color-coded based on the predicted PFAM domains and signal peptide cleavage site as well as modular organization previously described by Nicolay et al. (2015): an N-terminal signal peptide in red, a secreted mature passenger domain in green, and a C-terminal translocator domain in cyan with an upstream α-helical linker in purple. Orange spheres stand for amino acid residues that are subject to strong positive selection (posterior probability > 95%).