title: Quantitative and Functional Phosphoproteomic Analysis Reveals that Ethylene Regulates Water Transport via the C-Terminal Phosphorylation of Aquaporin PIP2;1 in Arabidopsis.
abstract: Ethylene participates in the regulation of numerous cellular events and biological processes, including water loss, during leaf and flower petal wilting. The diverse ethylene responses may be regulated via dynamic interplays between protein phosphorylation/dephosphorylation and ubiquitin/26S proteasome-mediated protein degradation and protease cleavage. To address how ethylene alters protein phosphorylation through multi-furcated signaling pathways, we performed a (15)N stable isotope labelling-based, differential, and quantitative phosphoproteomics study on air- and ethylene-treated ethylene-insensitive Arabidopsis double loss-of-function mutant ein3-1/eil1-1. Among 535 non-redundant phosphopeptides identified, two and four phosphopeptides were up- and downregulated by ethylene, respectively. Ethylene-regulated phosphorylation of aquaporin PIP2;1 is positively correlated with the water flux rate and water loss in leaf. Genetic studies in combination with quantitative proteomics, immunoblot analysis, protoplast swelling/shrinking experiments, and leaf water loss assays on the transgenic plants expressing both the wild-type and S280A/S283A-mutated PIP2;1 in the both Col-0 and ein3eil1 genetic backgrounds suggest that ethylene increases water transport rate in Arabidopsis cells by enhancing S280/S283 phosphorylation at the C terminus of PIP2;1. Unknown kinase and/or phosphatase activities may participate in the initial up-regulation independent of the cellular functions of EIN3/EIL1. This finding contributes to our understanding of ethylene-regulated leaf wilting that is commonly observed during post-harvest storage of plant organs.
authors.affiliation: Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
authors.forename: Dongjin
authors.initials: D
authors.lastname: Qing
authors.affiliation: Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Yang
authors.affiliation: School of Life Science, Peking University, Beijing 100089, China.
authors.forename: Mingzhe
authors.initials: M
authors.lastname: Li
authors.affiliation: Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
authors.forename: Wai Shing
authors.initials: WS
authors.lastname: Wong
authors.affiliation: Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
authors.forename: Guangyu
authors.initials: G
authors.lastname: Guo
authors.affiliation: Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
authors.forename: Shichang
authors.initials: S
authors.lastname: Liu
authors.affiliation: School of Life Science, Peking University, Beijing 100089, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Guo
authors.affiliation: Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China. Electronic address: boningli@ust.hk.
authors.forename: Ning
authors.initials: N
authors.lastname: Li
mesh_terms: D020346:Aquaporins / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins; D005030:Ethylenes / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D040901:Proteomics; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism; D014867:Water / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C494589:EIL1 protein, Arabidopsis; C106987:EIN3 protein, Arabidopsis; D005030:Ethylenes; D009687:Nuclear Proteins; D014157:Transcription Factors; C491680:plasma membrane intrinsic protein 2 Arabidopsis; D014867:Water; C036216:ethylene
keywords: (15)N stable isotope labeling in Arabidopsis (SILIA); aquaporin; ethylene signaling; mass spectrometry; quantitative PTM proteomics; water transport