Plays an essential role in type IV pili and type II pseudopili formation by proteolytically removing the leader sequence from substrate proteins and subsequently monomethylating the alpha-amino group of the newly exposed N-terminal phenylalanine (PubMed:8096341, PubMed:8340405, PubMed:23255525). Substrates include proteins required for pilus biogenesis PilE, PilV, PilW, and PilX as well as some components of the type II general secretory apparatus GspG, GspH, GspI and GspJ (PubMed:8331069). Typically cleaves a -Gly-|-Phe- bond to release an N-terminal, basic peptide of 5-8 residues from type IV prepilin, and then N-methylates the new N-terminal amino group, the methyl donor being S-adenosyl-L-methionine. Zinc is required for the N-terminal methylation of the mature pilin, but not for signal peptide cleavage. Belongs to the peptidase A24 family.