Regulation of the Salmonella typhimurium metA gene by the metR protein and homocysteine.
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.
Mares
R
R
Department of Microbiology, University of Iowa, Iowa City 52242.
Urbanowski
M L
ML
Stauffer
G V
GV
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
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C058169:MetR protein, Bacteria; D015534:Trans-Activators; D006710:Homocysteine