Constitutive activation of the Escherichia coli Pho regulon upregulates rpoS translation in an Hfq-dependent fashion

Natividad Ruiz, Thomas J. Silhavy

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52 Scopus citations

Abstract

Regulation of the σ factor RpoS occurs at the levels of transcription, translation, and protein stability activity, and it determines whether Escherichia coli turns on or off the stationary-phase response. To better understand the regulation of RpoS, we conducted genetic screens and found that mutations in the pst locus cause accumulation of RpoS during exponential growth. The pst locus encodes for the components of the high-affinity transport system for inorganic phosphate (Pi), which is involved in sensing Pi levels in the environment. When the Pst transporter is compromised (either by mutation or by Pi starvation), the two-component system PhoBR activates the transcription of the Pho regulon, a subset of genes that encode proteins for transporting and metabolizing alternative phosphate sources. Our data show that strains carrying mutations which constitutively activate the Pho regulon have increased rpoS translation during exponential growth. This upregulation of rpoS translation is Hfq dependent, suggesting the involvement of a small regulatory RNA (sRNA). The transcription of this yet-to-be-identified sRNA is regulated by the PhoBR two-component system.

Original languageEnglish (US)
Pages (from-to)5984-5992
Number of pages9
JournalJournal of bacteriology
Volume185
Issue number20
DOIs
StatePublished - Oct 2003

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Molecular Biology

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