Short Communication

Archives of Microbiology

, Volume 185, Issue 3, pp 234-237

The effect of IHF on σ S selectivity of the phoA and pst promoters of Escherichia coli

  • Natalia Pasternak TaschnerAffiliated withDepartamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo
  • , Ezra YagilAffiliated withDepartment of Biochemistry, Tel-Aviv University
  • , Beny SpiraAffiliated withDepartamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo Email author 

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Abstract

The pst operon, a member of the PHO regulon of Escherichia coli, encodes a high-affinity phosphate transport system whose expression is induced when the cells enter a phase of phosphate starvation. The expression of pst is stimulated by the integration host factor (IHF). Transcription of the PHO regulon genes is initiated by the RNA polymerase complexed with σ D (Eσ D). Owing to a cytosine residue at position −13 of the pst promoter its transcription can also be initiated by Eσ S. Here, we show that inactivation of IHF in vivo abolishes the σ S-dependent transcription initiation of the pst operon, indicating that both −13C residue and IHF are required to confer on pst the ability to be transcribed by Eσ S. Introduction of a −13C residue in the promoter region of phoA, another PHO regulon gene that is not directly affected by IHF, did not affect its exclusive transcription initiation by Eσ D.

Keywords

PHO regulon pst operon IHF rpoS Escherichia coli