Synthesis, antimicrobial activity, and mechanistic studies of enterocin DD14, a leaderless two-peptide bacteriocin

Bacteriocins are promising alternatives to antibiotics in the food, veterinary and medical sectors, but their study and use is often hampered by the low yields and high costs associated with their purification from naturally occurring bacteria. Chemical synthesis has emerged as a means to overcome this limitation and design more active variants. In this study, microwave-assisted solid-phase peptide synthesis was used to produce the leaderless two-peptide bacteriocin enterocin DD14 (EntDD14), composed of EntDD14A (44 amino acids) and EntDD14B (43 amino acids). The resulting synthetic peptides, syn -EntDD14A and syn-EntDD14B, were tested against Gram-positive bacteria including Listeria, Staphylococcus and Enterococcus strains. Both peptides were found to be necessary for optimal, but not synergistic, antibacterial activity and to act through a pore-forming mechanism. Both peptides exhibited moderate cytotoxicity against eukaryotic cells. • The EntDD14 two-peptide bacteriocin is composed by EntDD14A and EntDD14B. • Microwave-assisted solid-phase peptide synthesis of EntDD14A and EntDD14B peptides. • EntDD14A and EntDD14B peptides are necessary for optimal antibacterial, but not for synergistic, activity. • EntDD14A and EntDD14B peptides act through a pore-forming mechanism. • EntDD14A and EntDD14B peptides are moderately cytotoxic to eukaryotic cells.