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. 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. Deletion mutants are unable to secrete several extracellular degradative enzymes including the cytolysin/hemolysin tthat remains in the periplasmic space (PubMed:18604505). It results also in significant decreases in host cell cytotoxicity, adherence and virulence in a mouse mode (PubMed:9826339). Belongs to the peptidase A24 family.