Identical, independent, and opposing roles of ppGpp and DksA in Escherichia coli

  • Magnusson L
  • Gummesson B
  • Joksimović P
 et al. 
  • 103


    Mendeley users who have this article in their library.
  • 96


    Citations of this article.


The recent discovery that the protein DksA acts as a coregulator of genes controlled by ppGpp led us to investigate the similarities and differences between the relaxed phenotype of a ppGpp-deficient mutant and the phenotype of a strain lacking DksA. We demonstrate that the absence of DksA and ppGpp has similar effects on many of the observed phenotypes but that DksA and ppGpp also have independent and sometimes opposing roles in the cell. Specifically, we show that overexpression of DksA can compensate for the loss of ppGpp with respect to transcription of the promoters P(uspA), P(livJ), and P(rrnBP1) as well as amino acid auxotrophy, cell-cell aggregation, motility, filamentation, and stationary phase morphology, suggesting that DksA can function without ppGpp in regulating gene expression. In addition, ppGpp and DksA have opposing effects on adhesion. In the course of our analysis, we also discovered new features of the relaxed mutant, namely, defects in cell-cell aggregation and motility.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Lisa U. Magnusson

  • Bertil Gummesson

  • Predrag Joksimović

  • Anne Farewell

  • Thomas Nyström

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free