title: MetJ-mediated regulation of the Salmonella typhimurium metE and metR genes occurs through a common operator region.
abstract: In Salmonella typhimurium the metE and metR promoters overlap and are divergently transcribed. Three tandem repeats of an 8 bp sequence defined previously as the metE operator site for MetJ-mediated repression also overlap the -35 region of the metR promoter. Starting with a metE-lacZ.metR-galK double gene fusion, site-directed mutagenesis was used to change nucleotides in each of the repeat units from the consensus sequence. Each mutation, along with the wild-type metE-lacZ.metR-galK gene fusion, was cloned into phage lambda gt2. Regulation of the metE and metR genes was examined by measuring beta-galactosidase and galactokinase levels in Escherichia coli strains lysogenized with phage carrying the wild-type and mutant fusions. Mutations in each of the 8 bp repeat units disrupt MetJ-mediated repression for both the metE-lacZ and metR-galK gene fusions, suggesting that the metE and metR genes share a common operator site for the MetJ repressor.
authors: Department of Microbiology, University of Iowa, Iowa City 52242.
authors: W F
authors: WF
authors: Wu
authors: M L
authors: ML
authors: Urbanowski
authors: G V
authors: GV
authors: Stauffer
mesh_terms: D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D001426:Bacterial Proteins / Q000096:biosynthesis*; D001483:Base Sequence; D004794:Enzyme Repression / Q000235:genetics; D029968:Escherichia coli Proteins; D005686:Galactokinase / Q000096:biosynthesis / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D008780:Methyltransferases; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009875:Operator Regions, Genetic / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics*; D012486:Salmonella typhimurium / Q000235:genetics*; D015534:Trans-Activators / Q000096:biosynthesis*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C058169:MetR protein, Bacteria; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; C060486:methionine repressor protein, Bacteria; C489220:methionine repressor protein, E coli; D008780:Methyltransferases; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; C058170:metE protein, E coli; D005686:Galactokinase; D001616:beta-Galactosidase