peptide antibiotic microcin J25 PubChem:10793809 antibiotic_resistance ChEBI:203056 ARO:3003951 ChEMBL:CHEMBL1945674 Microcin J25 is a peptide antibiotic that inhibits transcription by bacterial RNA polymerase. MccJ25 is produced by Escherichia coli strains that harbor a plasmid-borne antibiotic-synthesis and antibiotic-export cassette, consisting of a gene for MccJ25 precursor (a 58 residue linear peptide), two genes for factors that process MccJ25 precursor into MccJ25, and one gene for export of MccJ25. MccJ25