Publication Abstract from PubMed
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 A 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.
Phosphorylation-independent interaction between 14-3-3 and exoenzyme S: from structure to pathogenesis.,Ottmann C, Yasmin L, Weyand M, Veesenmeyer JL, Diaz MH, Palmer RH, Francis MS, Hauser AR, Wittinghofer A, Hallberg B EMBO J. 2007 Feb 7;26(3):902-13. Epub 2007 Jan 18. PMID:17235285[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
