Escherichia coliMicrocin B17 as a chassis for the development of novel antimicrobial peptides

Abstract Antimicrobial resistance remains an urgent and growing global health problem. Peptides with antimicrobial activity are widespread in nature but are rarely harnessed for application, making them an underexplored and untapped resource. Many harbor post-translational modifications, which are essential for function and have evolved alongside specialized export and immunity machineries – leading to the current paradigm that natural sequences cannot be changed, and curtailing their development as antimicrobial agents. Nonetheless, we found sufficient ambiguity in literature to question if that remained true for E. coli MccB17. We demonstrate that its natural machinery for synthesis, export and immunity, can be co-opted as a platform for novel azole-modified antimicrobial peptide discovery. We show that the sequence space available for exploration is large and densely populated with functional sequences. One-Sentence Summary E. coli can be harnessed as an in vivo platform for the isolation of novel antimicrobial azole-modified peptides.