title: Lambda placMu insertions in genes of the leucine regulon: extension of the regulon to genes not regulated by leucine.
abstract: The leucine regulon coordinates the expression of several Escherichia coli genes according to the presence of exogenous leucine, which interacts with the lrp gene product, Lrp. We isolated and characterized 22 strains with lambda placMu insertions in Lrp-regulated genes. Lrp and leucine influenced gene expression in a surprising variety of ways. We identified two genes that are regulated by Lrp and not affected by L-leucine. We therefore rename this the leucine-lrp regulon. Genes coding for glycine cleavage and leucine biosynthesis enzymes have been identified as members of the leucine-lrp regulon. We suggest that the lrp gene product activates genes needed for growth in minimal medium, and we show that the gene is repressed by its own product and is highly repressed during growth in rich medium.
authors.affiliation: Department of Biological Sciences, Concordia University, Montreal, Quebec, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Lin
authors.forename: R
authors.initials: R
authors.lastname: D'Ari
authors.forename: E B
authors.initials: EB
authors.lastname: Newman
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D010583:Bacteriophage mu; D002244:Carbon / Q000378:metabolism; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005998:Glycine / Q000378:metabolism; D007930:Leucine / Q000502:physiology*; D051756:Leucine-Responsive Regulatory Protein; D016296:Mutagenesis; D009876:Operon; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C497278:Lrp protein, E coli; D014157:Transcription Factors; D051756:Leucine-Responsive Regulatory Protein; D002244:Carbon; D007930:Leucine; D005998:Glycine