Phosphorylation-independent interaction between 14-3-3 and exoenzyme S: From structure to pathogenesis

Christian Ottmann, Lubna Yasmin, Michael Weyand, Jeffrey L. Veesenmeyer, Maureen H. Diaz, Ruth H. Palmer, Matthew S. Francis, Alan R. Hauser, Alfred Wittinghofer, Bengt Hallberg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


14-3-3 proteins are phosphoserine/phosphothreonine-recognizing adapter proteins that regulate the activity of a vast array of targets. There are also examples of 14-3-3 proteins binding their targets via unphosphorylated motifs. Here we present a structural and biological investigation of the phosphorylation-independent interaction between 14-3-3 and exoenzyme S (ExoS), an ADP-ribosyltransferase toxin of Pseudomonas aeruginosa. ExoS binds to 14-3-3 in a novel binding mode mostly relying on hydrophobic contacts. The 1.5 Å crystal structure is supported by cytotoxicity analysis, which reveals that substitution of the corresponding hydrophobic residues significantly weakens the ability of ExoS to modify the endogenous targets RAS/RAP1 and to induce cell death. Furthermore, mutation of key residues within the ExoS binding site for 14-3-3 impairs virulence in a mouse pneumonia model. In conclusion, we show that ExoS binds 14-3-3 in a novel reversed orientation that is primarily dependent on hydrophobic residues. This interaction is phosphorylation independent and is required for the function of ExoS.

Original languageEnglish (US)
Pages (from-to)902-913
Number of pages12
JournalEMBO Journal
Issue number3
StatePublished - Feb 7 2007


  • ADP-ribosylation
  • Coenzyme binding site
  • Cytotoxicity
  • Pseudomonas aeruginosa
  • Structural analysis

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)


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