Structure of F-pili: reassessment of the symmetry.

Reassessment of the X-ray fibre diffraction patterns of F-pili using a more accurate subunit molecular weight suggests that subunits in F-pili are related by a fivefold rotation axis around the pilus axis. The identity of this fivefold symmetry with the fivefold rotation axis that relates the subunits in fd bacteriophage supports a simple model for tip-to-tip adsorption of bacteriophage to pili.