title: Regulation of enterobactin iron transport in Escherichia coli: characterization of ent::Mu d(Apr lac) operon fusions.
abstract: The vector Mu d(Apr lac) was utilized to construct operon fusions in the Escherichia coli enterobactin (ent) biosynthetic and transport genes. Enzyme assays indicated a 5- to 15-fold increase in the expression of beta-galactosidase when the fusion strains were grown under iron-deficient conditions. The polarity effects seen by Mu d insertions into entA, entC, and entE were consistent with a single operon, entA(CGB)E. The direction of transcription from iron-regulated promoters was determined by directional transfer of selected genetic markers after the insertion of F'ts114 lac+. Regulatory mutants were isolated in the fusion strains by the selection for constitutive expression of beta-galactosidase and the iron-regulated outer membrane proteins.
mesh_terms: D001692:Biological Transport; D004274:DNA, Recombinant; D004758:Enterobactin / Q000096:biosynthesis / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D005809:Genes, Regulator; D007501:Iron / Q000378:metabolism*; D009876:Operon; D012694:Serine / Q000031:analogs & derivatives*; D014158:Transcription, Genetic
chemical_list: D004274:DNA, Recombinant; D004758:Enterobactin; D012694:Serine; D007501:Iron