title: Pattern of induction of colicin E9 synthesis by sub MIC of Norfloxacin antibiotic.
abstract: The presence of dual SOS boxes in the regulatory region of the most of colicin operons confines synthesis of colicin to times of stress, presumably to reduce the cost of its production. However, in presence of certain inducing agents, such as antibiotics, this tight control of colicin operon is usually lost. Although synthesis of most of colicins is known to be regulated by SOS response of host cell, different patterns of induction from distinct colicins against various inducing agents have been shown in recent years. In this study, we investigated the induction pattern of enzymatic colicin E9 (ColE9) synthesis following treatment with various concentrations (sub MICs) of the Norfloxacin (NOR) using pSBM23 construct which carries transcriptional fusion of SOS inducible promoter of pColE9 (ColE9p) and a fluorescent reporter gene (gfpmut2) into kanamycin resistant pColE9-J plasmid. Flow cytomtry analysis of the Escherichia coli cells containing pSBM23, following treatment with various concentrations showed that the SOS response mediated induction of the synthesis of ColE9 happens in a dose-dependent manner. In summary, our results suggest that the presence, even in a minute amount, of SOS response inducing agents such as fluoroquinolone antibiotic in natural habitat of colicinogenic population can promote such a costly antagonistic behaviour of microbes.
authors.affiliation: School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University of Nottingham, University Park, NG7 2RD, United Kingdom; Department of Microbiology, University of Sindh, Jamshoro, Pakistan. Electronic address: microhira@hotmail.com.
authors.forename: Shaista
authors.initials: S
authors.lastname: Bano
authors.forename: Mireille
authors.initials: M
authors.lastname: Vankemmelbeke
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Penfold
authors.forename: Richard
authors.initials: R
authors.lastname: James
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism*; D019677:Artificial Gene Fusion; D003087:Colicins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D009643:Norfloxacin / Q000378:metabolism*; D013014:SOS Response, Genetics
chemical_list: D000900:Anti-Bacterial Agents; D003087:Colicins; D049452:Green Fluorescent Proteins; D009643:Norfloxacin
keywords: Colicin E9; Flow cytometry; Fluorescent reporter system; Norfloxacin