title: Genetic evidence for an activator required for induction of colicin-like bacteriocin 28b production in Serratia marcescens by DNA-damaging agents.
abstract: Bacteriocin 28b production is induced by mitomycin in wild-type Serratia marcescens 2170 but not in Escherichia coli harboring the bacteriocin 28b structural gene (bss). Studies with a bss-lacZ transcriptional fusion showed that mitomycin increased the level of bss gene transcription in S. marcescens but not in the E. coli background. A S. marcescens Tn5 insertion mutant was obtained (S. marcescens 2170 reg::Tn5) whose bacteriocin 28b production and bss gene transcription were not increased by mitomycin treatment. Cloning and DNA sequencing of the mutated region showed that the Tn5 insertion was flanked by an SOS box sequence and three genes that are probably cotranscribed (regA, regB, and regC). These three genes had homology to phage holins, phage lysozymes, and the Ogr transcriptional activator of P2 and related bacteriophages, respectively. Recombinant plasmid containing this wild-type DNA region complemented the reg::Tn5 regulatory mutant. A transcriptional fusion between a 157-bp DNA fragment, containing the apparent SOS box upstream of the regA gene, and the cat gene showed increased chloramphenicol acetyltransferase activity upon mitomycin treatment. Upstream of the bss gene, a sequence similar to the consensus sequence proposed to bind Ogr protein was found, but no sequence similar to an SOS box was detected. Our results suggest that transcriptional induction of bacteriocin 28b upon mitomycin treatment is mediated by the regC gene whose own transcription would be LexA dependent.
authors.affiliation: Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Barcelona, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Ferrer
authors.forename: M B
authors.initials: MB
authors.lastname: Viejo
authors.forename: J F
authors.initials: JF
authors.lastname: Guasch
authors.forename: J
authors.initials: J
authors.lastname: Enfedaque
authors.forename: M
authors.initials: M
authors.lastname: Regué
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001430:Bacteriocins / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D004249:DNA Damage; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D008937:Mitomycins / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D011494:Protein Kinases; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013014:SOS Response, Genetics; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D012706:Serratia marcescens / Q000187:drug effects / Q000235:genetics*; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D001430:Bacteriocins; D008937:Mitomycins; D045322:Photosynthetic Reaction Center Complex Proteins; D011993:Recombinant Fusion Proteins; C072722:RegA protein, Bacteria; C091081:RegB protein, Rhodobacter; C098045:RegC protein, Serratia marcescens; D015534:Trans-Activators; D014157:Transcription Factors; C076729:bss protein, bacteria; D011494:Protein Kinases