PspF and IHF bind co-operatively in the psp promoter-regulatory region of Escherichia coli.
PspF bound to the psp enhancer activates E sigma54 holoenzyme-dependent transcription of the Escherichia coli phage-shock protein (psp) operon and autogenously represses its own sigma70-dependent transcription, thereby keeping its concentration at a low level. It has been demonstrated previously that integration host factor (IHF) bound to a DNA site located between the psp core promoter and the PspF binding sites stimulates psp expression. We show here that wild-type IHF strongly retards DNA containing the psp promoter region. In vitro, PspF binding to the psp enhancer facilitates IHF binding, while IHF binding to the pspF-pspA-E promoter-regulatory region increases the efficacy of PspF binding to the upstream activating sequences (UASs). This is the first demonstration of co-operative binding of an activator and IHF in a sigma54-dependent system. In the absence of IHF, in vivo autoregulation of pspF transcription is lifted and, consequently, PspF production is increased, indicating that IHF enhances PspF binding to the psp enhancer in vivo.
Jovanovic
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Laboratory of Genetics, The Rockefeller University, New York, NY 10021, USA.
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D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics*; D034982:Integration Host Factors; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015534:Trans-Activators / Q000378:metabolism*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D034982:Integration Host Factors; C098954:PspF protein, E coli; D015534:Trans-Activators; C069816:phage shock protein, Bacteria