The relation between ppGpp and the PHO regulon in Escherichia coli

B. Spira, E. Yagil*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Starving of Escherichia coli cells for inorganic orthophosphate (Pi) results in the accumulation of spoT-dependent ppGpp and induces the expression of genes of the PHO regulon. In a ΔrelA ΔspoT strain that is unable to accumulate ppGpp the expression of two genes (phoA and pstS) that belong to the PHO regulon is impaired, even in constitutive mutants. The transcription of phoA and of pstS is not affected in the ppGpp0 strain, and therefore this impairment is due to a post-transcriptional defect. Conversely, overexpression of ppGpp inhibits transcription of these two PHO regulon genes. In phoB mutants, the accumulation of ppGpp during Pi starvation is diminished, suggesting that PhoB or one of the PHO products is involved in the control of ppGpp accumulation. We propose that the presence of ppGpp in the cell, but not its accumulation as a result of the starvation stress, is important for the expression of the PHO genes.

Original languageEnglish
Pages (from-to)469-477
Number of pages9
JournalMolecular and General Genetics
Issue number4
StatePublished - 1998


FundersFunder number
Lion Foundation


    • Alkaline phosphatase
    • Escherichia coli
    • PHO-regulon
    • ppGpp

    Cite this