title: Single independent operator sites are involved in the genetic switch of the Lactobacillus delbrueckii bacteriophage mv4.
abstract: The lysogeny region of the Lactobacillus delbrueckii bacteriophage mv4 contains two divergently oriented ORFs coding for the Rep (221 aa) and Tec (64 aa) proteins. The transcription of these two genes was analysed by primer extension and Northern blot experiments on lysogenic strains. The location of the transcription initiation sites of rep and tec in the intergenic region allowed the identification of the divergently oriented non overlapping promoters P(rep) and P(tec). Transcriptional fusions analysis showed that Rep negatively regulates the P(tec) promoter and activates its own transcription, and that Tec is a negative regulator of the two promoters. As demonstrated by gel mobility shift assays, the repressor Rep binds to a single specific 17 bp site located between the P(tec) -10 and -35 regions whereas Tec binds to a single specific 40 bp long complex operator site located between the two promoters. The presence of a single specific operator site for each repressor in the intergenic region is an unusual feature.
authors.affiliation: Laboratoire de Microbiologie et de Génétique Moléculaire du CNRS, Université Paul Sabatier, Bat IBCG, 118 route de Narbonne, Toulouse Cedex, France.
authors.forename: Michèle
authors.initials: M
authors.lastname: Coddeville
authors.forename: Frédéric
authors.initials: F
authors.lastname: Auvray
authors.forename: Merja
authors.initials: M
authors.lastname: Mikkonen
authors.forename: Paul
authors.initials: P
authors.lastname: Ritzenthaler
mesh_terms: D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000821:virology; D016679:Genome, Viral; D048668:Lactobacillus delbrueckii / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D008242:Lysogeny / Q000235:genetics; D008969:Molecular Sequence Data; D009875:Operator Regions, Genetic; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D004279:DNA, Viral; D012097:Repressor Proteins; D014764:Viral Proteins