Function
Repeated PapE subunits make up the thin (2 nm in diameter) tip fibrillum of the P pilus. Subunits are arranged in a open helical conformation. Pili with a defective papE gene have low adhesive capacity or none; however, the binding property of the whole cell is not affected. Pili are polar filaments radiating from the surface of the bacterium to a length of 0.5-1.5 micrometers and numbering 100-300 per cell, and enable bacteria to colonize the epithelium of specific host organs.