Peptide antibiotic that functions through inhibition of the bacterial DNA-dependent RNA polymerase (RNAP) (PubMed:11443089, PubMed:12401787). Inhibits transcription by binding deep within RNAP secondary channel, where it sterically blocks the folding of the trigger loop, which is essential for efficient catalysis (PubMed:15200952, PubMed:30626643). In addition, it also seems to restrict access of nucleotide substrates to the catalytic center, and shows a partially competitive mode of inhibition with them (PubMed:15200952, PubMed:30626643). Exhibits potent bacteriocidal activity against a range of Enterobacteriaceae, including several pathogenic E.coli, Salmonella and Shigella strains (PubMed:1429464). Also acts on the cytoplasmic membrane of Salmonella newport, producing alteration of membrane permeability and disruption of the subsequent gradient dissipation, which inhibits several processes essential for cell viability, such as oxygen consumption (PubMed:11731133). Induces bacterial filamentation in susceptible cells in a non-SOS-dependent way, but this phenotype may result from impaired transcription of genes coding for cell division proteins (PubMed:1429464). At the onset of stationary growth phase. Was originally thought to have a head-to-tail cyclic structure, but actually has a threaded side chain-to-backbone ring structure that is penetrated by the C-terminal tail in a noose-like motif. Entanglement - Issue 72 of July 2006