A sequence-induced superhelical DNA segment serves as transcriptional enhancer.
The initiation of transcription at the sigma 54-dependent promoter glnAp2 of Escherichia coli is activated by the protein NR1(NTRC)-phosphate, which binds to two sites located upstream of the promoter that together constitute an enhancer. The cooperative binding facilitates the oligomerization of NR1-phosphate endowing it with the ATPase activity required for its ability to serve as transcriptional activator. We show here that these sites can be replaced by sequence-dependent superhelical inserts, lacking any homology to the nucleotide sequence of the enhancers. These superhelical inserts, irrespective of their chirality, are as effective as the paired sites in binding NR1-phosphate and in stimulating its oligomerization. We conclude that a specific sequence of nucleotides and the three-dimensional structure of DNA can determine its affinity for the NR1 activator protein capable of binding to DNA.
Department of Biology Massachusetts Institute of Technology, Cambridge 02139.
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Brahms
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Magasanik
D000251:Adenosine Triphosphatases / Q000378:metabolism; D001426:Bacterial Proteins; D001483:Base Sequence; D001665:Binding Sites; D004278:DNA, Superhelical / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology; D009690:Nucleic Acid Conformation; D051922:PII Nitrogen Regulatory Proteins; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D051877:RNA Polymerase Sigma 54; D012808:Sigma Factor / Q000378:metabolism; D013698:Templates, Genetic; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics*
D001426:Bacterial Proteins; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D051922:PII Nitrogen Regulatory Proteins; D012808:Sigma Factor; D015534:Trans-Activators; D014157:Transcription Factors; C497876:glnG protein, E coli; C497751:rpoN protein, E coli; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54; D000251:Adenosine Triphosphatases