title: Role of integration host factor in the regulation of the glnHp2 promoter of Escherichia coli.
abstract: The glnHPQ operon of Escherichia coli encodes components of the high-affinity glutamine transport system. One of the two promoters of this operon, glnHp2, is responsible for expression of the operon under nitrogen-limiting conditions. The general nitrogen regulatory protein (NRI) binds to two overlapping sites centered at -109 and -122 from the transcription start site and, when phosphorylated, activates transcription of glnHp2 by catalyzing isomerization of the closed sigma 54-RNA polymerase promoter complex to an open complex. The DNA-bending protein integration host factor (IHF) binds to a site immediately upstream of glnHp2 and enhances the activation of open complex formation by NRI phosphate. The NRI-binding sites can be moved several hundred base pairs further upstream without altering the ability of NRI phosphate to activate open complex formation. We propose that the IHF-induced bend can facilitate or obstruct the interaction between NRI phosphate and the closed complex depending on the relative positions of NRI phosphate and sigma 54-RNA polymerase on the DNA.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: F
authors.initials: F
authors.lastname: Claverie-Martin
authors.forename: B
authors.initials: B
authors.lastname: Magasanik
mesh_terms: D001426:Bacterial Proteins; D001483:Base Sequence; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005973:Glutamine / Q000378:metabolism*; D019426:Integrases; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D051922:PII Nitrogen Regulatory Proteins; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015183:Restriction Mapping; D012808:Sigma Factor / Q000235:genetics; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D015345:Oligonucleotide Probes; D051922:PII Nitrogen Regulatory Proteins; D012808:Sigma Factor; D015534:Trans-Activators; D014157:Transcription Factors; C497876:glnG protein, E coli; D005973:Glutamine; D004254:DNA Nucleotidyltransferases; D019426:Integrases; D012321:DNA-Directed RNA Polymerases