Figure 2
The α1–α2 loop and adjecent residues in immunity proteins adopt different conformations in members of the Im7-like family. (A) The immunity protein “α1–α2 motif”, defined as the structurally-dissimilar region with observed Cα distances of more than 1.5 Å between at least two of the structures. The representative structures from the Im7-like family (Fig. 1A) were superimposed and their α1–α2 motifs were colored as follows: Im7, green; Im9 and Im2, pink; ImS2, cyan; ImAP41, orange. (B) Close-up of the α1–α2 motif, rotated 45° about the Y-axis relative to (A). Colicins and immunity proteins are colored pink and light blue, respectively. (C) Structure-based sequence alignment of the Im7-like family. The structurally-dissimilar α1–α2 motifs are color-coded as in A. Im7 secondary structure elements are marked above and below the alignment. Note that only the Im9 and Im2 α1–α2 motifs were structurally-similar.
