title: MAPK target networks in Arabidopsis thaliana revealed using functional protein microarrays.
abstract: Signaling through mitogen-activated protein kinases (MPKs) cascades is a complex and fundamental process in eukaryotes, requiring MPK-activating kinases (MKKs) and MKK-activating kinases (MKKKs). However, to date only a limited number of MKK-MPK interactions and MPK phosphorylation substrates have been revealed. We determined which Arabidopsis thaliana MKKs preferentially activate 10 different MPKs in vivo and used the activated MPKs to probe high-density protein microarrays to determine their phosphorylation targets. Our analyses revealed known and novel signaling modules encompassing 570 MPK phosphorylation substrates; these substrates were enriched in transcription factors involved in the regulation of development, defense, and stress responses. Selected MPK substrates were validated by in planta reconstitution experiments. A subset of activated and wild-type MKKs induced cell death, indicating a possible role for these MKKs in the regulation of cell death. Interestingly, MKK7- and MKK9-induced death requires Sgt1, a known regulator of cell death induced during plant innate immunity. Our predicted MKK-MPK phosphorylation network constitutes a valuable resource to understand the function and specificity of MPK signaling systems.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA.
authors.forename: Sorina C
authors.initials: SC
authors.lastname: Popescu
authors.forename: George V
authors.initials: GV
authors.lastname: Popescu
authors.forename: Shawn
authors.initials: S
authors.lastname: Bachan
authors.forename: Zimei
authors.initials: Z
authors.lastname: Zhang
authors.forename: Mark
authors.initials: M
authors.lastname: Gerstein
authors.forename: Michael
authors.initials: M
authors.lastname: Snyder
authors.forename: Savithramma P
authors.initials: SP
authors.lastname: Dinesh-Kumar
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000254:growth & development / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism; D016923:Cell Death / Q000502:physiology; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks / Q000235:genetics / Q000502:physiology*; D005964:Glucosyltransferases; D048688:MAP Kinase Kinase 7 / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D040081:Protein Array Analysis; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014026:Nicotiana / Q000201:enzymology; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D005964:Glucosyltransferases; C515668:SGT1 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; C512166:BUD1 protein, Arabidopsis; D048688:MAP Kinase Kinase 7; C527379:MKK9 protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases