Figure 7.

Circular Permutation of ToxA.

(A) Topological comparison of ToxA and the tenth domain of fibronectin (FnIII₁₀) shown as a representative for the FnIII domain using the strand nomenclature proposed by Leahy et al. (1992). Open arrows and rectangles represent elements that are common to both of the structures, and striped arrows represent elements unique to each structure. The positions of the conserved RGD residues are also indicated.

(B) Stereoview of the ToxA (pink)/FnIII₁₀ (blue) comparison, with the unique elements of each chain indicated (striped). The Cα positions of RGD residues are shown as semitransparent spheres. The view is identical to that of Figure 3A. The secondary structural elements are labeled in both panels. The connection of the N and C termini (dashed line) and the cleaving of the β6-β7 loop (arrowhead) define the changes involved in the circular permutation.