Lasso peptides, a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) secreted by bacteria, have antimicrobial activity. Here, a novel lasso peptide, microcin Y (MccY), was discovered and characterized. The gene cluster for MccY synthesis was cloned for expression in Escherichia coli. This peptide was purified by HPLC and characterized by Q-TOF. MIC assays showed that some Bacillus, Staphylococcus, Pseudomonas, Shigella, and Salmonella strains were sensitive to MccY. Interestingly, Salmonellatyphimurium and Salmonella infantis were efficiently inhibited by MccY, while they were not affected by MccJ25, a lasso peptide that has antibacterial effects on many Salmonella strains. Furthermore, MccY-resistant strains of S. typhimurium were screened, and mutations were found in FhuA and SbmA, indicating the importance of these transporters for MccY absorption. This novel peptide can greatly broaden the antimicrobial spectrum of MccJ25 in Salmonella and is expected to be used in food preservation and animal feed additive areas.
Keywords: Salmonella; antibacterial activity; ferrichrome transporter; lasso peptide; microcin.