Predicted three-dimensional structure of RicA. The left-handed β-helix is composed of three β sheets connected by short loops. One of these loops is the IGFP loop (Ile69 to Pro73). The structure is shown as a ribbon aligned to the backbone of the model (made using the MacPyMol program), comprising residues Ile3 to Arg170. A “top view” is shown in the middle part of the figure. The three β sheets form a triangle in this view. On the right part of the figure, the accessible surface of the predicted trimer is depicted, with a monomer ribbon shown by transparency.