Phosphorylation-independent interaction between 14-3-3 and exoenzyme S: from structure to pathogenesis.
2007 (English)In: EMBO Journal, ISSN 0261-4189, Vol. 26, no 3, 902-913 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2007. Vol. 26, no 3, 902-913 p.
14-3-3 Proteins/*genetics/*metabolism, ADP Ribose Transferases/*metabolism, Animals, Bacterial Toxins/*metabolism, Blotting; Western, Crystallography, DNA Primers, Female, Hela Cells, Humans, Mice, Mice; Inbred BALB C, Models; Molecular, Molecular Conformation, Mutation/genetics, Pneumonia/*microbiology, Protein Binding, Pseudomonas aeruginosa/enzymology/*pathogenicity, rap1 GTP-Binding Proteins/metabolism
IdentifiersURN: urn:nbn:se:umu:diva-18052DOI: 10.1038/sj.emboj.7601530PubMedID: 17235285OAI: oai:DiVA.org:umu-18052DiVA: diva2:157725