title: Identification of novel PAMP-triggered phosphorylation and dephosphorylation events in Arabidopsis thaliana by quantitative phosphoproteomic analysis.
abstract: Signaling cascades rely strongly on protein kinase-mediated substrate phosphorylation. Currently a major challenge in signal transduction research is to obtain high confidence substrate phosphorylation sites and assign them to specific kinases. In response to bacterial flagellin, a pathogen-associated molecular pattern (PAMP), we searched for rapidly phosphorylated proteins in Arabidopsis thaliana by combining multistage activation (MSA) and electron transfer dissociation (ETD) fragmentation modes, which generate complementary spectra and identify phosphopeptide sites with increased reliability. Of a total of 825 phosphopeptides, we identified 58 to be differentially phosphorylated. These peptides harbor kinase motifs of mitogen-activated protein kinases (MAPKs) and calcium-dependent protein kinases (CDPKs), as well as yet unknown protein kinases. Importantly, 12 of the phosphopeptides show reduced phosphorylation upon flagellin treatment. Since protein abundance levels did not change, these results indicate that flagellin induces not only various protein kinases but also protein phosphatases, even though a scenario of inhibited kinase activity may also be possible.
authors.affiliation: CNRS, UMR 8587, boulevard François Mitterrand, 91025 Evry, France.
authors.forename: Naganand
authors.initials: N
authors.lastname: Rayapuram
authors.forename: Ludovic
authors.initials: L
authors.lastname: Bonhomme
authors.forename: Jean
authors.initials: J
authors.lastname: Bigeard
authors.forename: Kahina
authors.initials: K
authors.lastname: Haddadou
authors.forename: Cédric
authors.initials: C
authors.lastname: Przybylski
authors.forename: Heribert
authors.initials: H
authors.lastname: Hirt
authors.forename: Delphine
authors.initials: D
authors.lastname: Pflieger
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism* / Q000502:physiology; D002853:Chromatography, Liquid; D005408:Flagellin / Q000378:metabolism*; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D010766:Phosphorylation; D020543:Proteome / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D040901:Proteomics; D053719:Tandem Mass Spectrometry
chemical_list: D010750:Phosphoproteins; D020543:Proteome; D005408:Flagellin