title: Regulation of the Salmonella typhimurium metA gene by the metR protein and homocysteine.
abstract: The DNA sequence of the Salmonella typhimurium metA control region is presented. S1 nuclease mapping was used to determine the transcription initiation site. By measuring beta-galactosidase levels in Escherichia coli strains lysogenized with lambda phage carrying a metA-lacZ gene fusion, the MetR protein was shown to activate the metA gene. Homocysteine, an intermediate in methionine biosynthesis, plays a negative role in the MetR-mediated activation mechanism. Gel mobility shift assays and DNase I protection experiments showed that the MetR protein binds to a DNA fragment carrying the metA control region and protects a 26-bp region beginning 9 bp upstream of the -35 promoter sequence.
authors.affiliation: Department of Microbiology, University of Iowa, Iowa City 52242.
authors.forename: R
authors.initials: R
authors.lastname: Mares
authors.forename: M L
authors.initials: ML
authors.lastname: Urbanowski
authors.forename: G V
authors.initials: GV
authors.lastname: Stauffer
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006710:Homocysteine / Q000235:genetics* / Q000502:physiology; D007763:Lac Operon; D008969:Molecular Sequence Data; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid; D012486:Salmonella typhimurium / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C058169:MetR protein, Bacteria; D015534:Trans-Activators; D006710:Homocysteine