Open AccessA nonphosphorylated 14‐3‐3 binding motif on exoenzyme S that is functional in vivo
Author(s) -
Henriksson Maria L.,
Francis Matthew S.,
Peden Alex,
Aili Margareta,
Stefansson Kristina,
Palmer Ruth,
Aitken Alastair,
Hallberg Bengt
Publication year - 2002
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1033.2002.03191.x
Subject(s) - microbiology and biotechnology , phosphorylation , gene isoform , cytoplasm , phosphatase , biology , peptide , in vivo , exoenzyme , plasma protein binding , kinase , protein–protein interaction , biochemistry , chemistry , enzyme , genetics , gene
14‐3‐3 proteins play an important role in a multitude of signalling pathways. The interactions between 14‐3‐3 and other signalling proteins, such as Raf and KSR (kinase suppressor of Ras), occur in a phospho‐specific manner. Recently, a phosphorylation‐independent interaction has been reported to occur between 14‐3‐3 and several proteins, for example 5‐phosphatase, p75NTR‐associated cell death executor (NADE) and the bacterial toxin Exoenzyme S (ExoS), an ADP‐ribosyltransferase from Pseudomonas aeruginosa . In this study we have identified the amino acid residues on ExoS, which are responsible for its specific interaction with 14‐3‐3. Furthermore, we show that a peptide derived from ExoS, containing the 14‐3‐3 interaction site, effectively competes out the interaction between ExoS and 14‐3‐3. In addition, competition with this peptide blocks ExoS modification of Ras in our Ras modification assay. We show that the ExoS protein interacts with all isoforms of the 14‐3‐3 family tested. Moreover, in vivo an ExoS protein lacking the 14‐3‐3 binding site has a reduced capacity to ADP ribosylate cytoplasmic proteins, e.g. Ras, and shows a reduced capacity to change the morphology of infected cells.