Characterization of corynacin K411, a leaderless bacteriocin from Corynebacterium jeikeium

Abstract Bacteriocins are ribosomally synthesized antimicrobial peptides that are emerging as natural preservatives and alternatives to conventional antibiotics in response to the growing threat of antimicrobial resistance. Here, we provide a comprehensive experimental characterization of corynacin K411, previously reported as K411/AucA. The corynacin K411 biosynthetic gene cluster encodes a set of proteins that support a coordinated system for peptide production, secretion, and self-immunity. Corynacin K411 exhibits potent activity against various bacteria, including the foodborne pathogen Listeria monocytogenes . It demonstrates stability across acidic and alkaline pH (pH 2 to 10) and high temperatures (37 °C and 60 °C). It exerts bactericidal activity by disrupting membrane integrity, causing leakage of nucleic acids, proteins, potassium and magnesium ions. Importantly, corynacin K411 is non-hemolytic and non-cytotoxic to human keratinocytes. In addition, it inhibits L. monocytogenes biofilm formation, reduces the biomass of pre-formed biofilms, and lowers bacterial cell counts in a milk preservation model system. Structural analysis of the AlphaFold-predicted three-dimensional structure indicates a saposin-like fold, consistent with other characterized saposin-like leaderless bacteriocins.