title: A large-scale protein phosphorylation analysis reveals novel phosphorylation motifs and phosphoregulatory networks in Arabidopsis.
abstract: Large-scale protein phosphorylation analysis by MS is emerging as a powerful tool in plant signal transduction research. However, our current understanding of the phosphorylation regulatory network in plants is still very limited. Here, we report on a proteome-wide profiling of phosphopeptides in nine-day-old Arabidopsis (Arabidopsis thaliana) seedlings by using an enrichment method combining the titanium (Ti(4+))-based IMAC and the RP-strong cation exchange (RP-SCX) biphasic trap column-based online RPLC. Through the duplicated RPLC-MS/MS analyses, we identified 5348 unique phosphopeptides for 2552 unique proteins. Among the phosphoproteins identified, 41% of them were first-time identified. Further evolutionary conservation and phosphorylation motif analyses of the phosphorylation sites discovered 100 highly conserved phosphorylation residues and identified 17 known and 14 novel motifs specific for Ser/Thr protein kinases. Gene ontology and pathway analyses revealed that many of the new identified phosphoproteins are important regulatory proteins that are involved in diverse biological processes, particularly in central metabolisms and cell signaling. Taken together, our results provided not only new insights into the complex phosphoregulatory network in plants but also important resources for future functional studies of protein phosphorylation in plant growth and development.
authors.affiliation: State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Bian
authors.forename: Kai
authors.initials: K
authors.lastname: Cheng
authors.forename: Li-Fei
authors.initials: LF
authors.lastname: Gu
authors.forename: Mingliang
authors.initials: M
authors.lastname: Ye
authors.forename: Hanfa
authors.initials: H
authors.lastname: Zou
authors.forename: Samuel Sai-Ming
authors.initials: SS
authors.lastname: Sun
authors.forename: Jun-Xian
authors.initials: JX
authors.lastname: He
mesh_terms: D020816:Amino Acid Motifs; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D040901:Proteomics
chemical_list: D029681:Arabidopsis Proteins; D010750:Phosphoproteins