The characteristics of peptide uptake in Streptococcus faecalis: studies on the transport of natural peptides and antibacterial phosphonopeptides.

Transport of natural peptides and antibacterial phosphonopeptide analogues was studied in Streptococcus faecalis ATCC 9790. Competition studies, and the isolation of peptide-transport deficient mutants, indicate the presence of two peptide permeases. One is a high-rate system used by dipeptides, and to a lesser extent tripeptides; the other is a low-rate oligopeptide system. Following uptake, peptides are cleaved and their amino acid residues may undergo rapid exodus. Different strains of S. faecalis differ in their rates of peptide transport.