Histidine operon deattenuation in dnaA mutants of Salmonella typhimurium correlates with a decrease in the gene dosage ratio between tRNA(His) and histidine biosynthetic loci.
Expression of the histidine operon of Salmonella typhimurium is increased in dnaA(Ts) mutants at 37 degrees C. This effect requires an intact his attenuator and can be suppressed by increasing the gene copy number of the hisR locus, which encodes the tRNA(His). We present data which suggest that the his deattenuation defect in dnaA(Ts) mutants results from the loss of a gene dosage gradient between the hisR locus, close to oriC, and the his operon, far from oriC. Some of the conclusions drawn here may apply to other operons as well.
Blanc-Potard
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AB
Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette Cedex, France.
Figueroa-Bossi
N
N
Bossi
L
L
D001426:Bacterial Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D029968:Escherichia coli Proteins; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial; D006639:Histidine / Q000096:biosynthesis*; D007763:Lac Operon; D009154:Mutation; D009876:Operon; D012354:RNA, Transfer, His / Q000235:genetics*; D011993:Recombinant Fusion Proteins; D012486:Salmonella typhimurium / Q000235:genetics*; D013489:Suppression, Genetic
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; C071702:DnaC protein, E coli; D029968:Escherichia coli Proteins; D012354:RNA, Transfer, His; D011993:Recombinant Fusion Proteins; D006639:Histidine