Major component of type IV bundle-forming pili (BFP) that plays a role in adherence to host cells and virulence. 10 to 100 laterally aligned filaments or bundle-forming pili coalesce into rope-like bundles. These form linkages between the bacteria within the enteropathogenic E.coli (EPEC) microcolonies that are attached to epithelial cells (By similarity). Deletion mutants cause significantly less diarrhea in volonteers. Belongs to the N-Me-Phe pilin family. The modified residue is misidentified as methionine.