FIGURE 7.

Sequence variation in PilJ. A, unrooted phylogenic tree of C. difficile strains by PilJ sequence. B, model of full-length PilJ. Polymorphic residues in PilJ are represented with side chains rendered as spheres, colored by the number of variations from the reference sequence within the set of 20 C. difficile strains compared here. The blue surface shows the area of each pilin occluded from solvent by the formation of a pilus fragment and hence potentially part of a pilin-pilin interface.