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A Quantitative Proteomic Analysis of Brassinosteroid-induced Protein Phosphorylation in Rice ( Oryza sativa L.)

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ABSTRACT

The group of polyhydroxysteroid phytohormones referred to as the brassinosteroids (BRs) is known to act on plant development and the stress response. BR signal transduction relies largely on protein phosphorylation. By employing a label-free, MS (Mass Spectrometry)-based phosphoproteomic approach, we report here the largest profiling of 4,034 phosphosites on 1,900 phosphoproteins from rice young seedlings and their dynamic response to BR. 1,821 proteins, including kinases, transcription factors and core components of BR and other hormone signaling pathways, were found to be differentially phosphorylated during the BR treatment. A Western blot analysis verified the differential phosphorylation of five of these proteins, implying that the MS-based phosphoproteomic data were robust. It is proposed that the dephosphorylation of gibberellin (GA) signaling components could represent an important mechanism for the BR-regulated antagonism to GA, and that BR influences the plant architecture of rice by regulating cellulose synthesis via phosphorylation.

No MeSH data available.


(A–E) Sub-network of all the DP proteins by using STRING and Cytoscape. The locus ID of the abbreviations in (A–E) could be seen in additional Supplementary Table S2.
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Figure 4: (A–E) Sub-network of all the DP proteins by using STRING and Cytoscape. The locus ID of the abbreviations in (A–E) could be seen in additional Supplementary Table S2.

Mentions: By using the String 10.05 (Search Tool for the Retrieval of Interacting Genes/Proteins) (Szklarczyk et al., 2015) and Cytoscape visualization (Shannon et al., 2003), we constructed PPI networks for DP kinases/phosphatases and all the BR induced DP proteins, respectively. Figure 4A depicted the sub-networks of DP kinases/phosphatases with high confidence score of 0.9. Eight PP2A phosphatases formed 11 edges (interaction relationships) sub-network, of which PP2A-2 (LOC_Os03g59060) and PP2Ac-4 (LOC_Os10g27050) were in the center. In Arabidopsis BR signaling, PP2As are critical phosphatases to dephosphorylate BZR1 and BZR2, which helps to retain the functional BZR1 and BZR2 in the nucleus and confer plants with BR response. The DP pattern suggested critical roles of these PP2As in BR response, whereas the predicted interaction relationships implied that PP2As may work in forms of protein complexes in BR signaling. A CDKG-2-CDKF-1-R2-SNT7 pathway was revealed in our PPI analysis. CDKG-2 (LOC_Os04g41100), CDKF-1 (LOC_Os06g22820), and R2 (LOC_Os05g32600) are cycling-dependent kinases functioning in cell proliferations, indicating this to be a key pathway in BR-regulated cell proliferation. In addition, we also detected a putative OsMEK1-MA3K.14-SMG1 pathway which is related to rice cell proliferation as well as stress resistance (Figure 4A). The full set of 1,821 DP proteins produced an interactome map composed of 459 nodes (proteins) and 946 edges. The various PPI sub-networks are associated with cellulose biosynthesis (Figure 4B), oxidation-reduction reactions (Figure 4C), phytohormone signaling (Figure 4D), and vascular ATP synthesis/transportation (Figure 4E).


A Quantitative Proteomic Analysis of Brassinosteroid-induced Protein Phosphorylation in Rice ( Oryza sativa L.)
(A–E) Sub-network of all the DP proteins by using STRING and Cytoscape. The locus ID of the abbreviations in (A–E) could be seen in additional Supplementary Table S2.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383725&req=5

Figure 4: (A–E) Sub-network of all the DP proteins by using STRING and Cytoscape. The locus ID of the abbreviations in (A–E) could be seen in additional Supplementary Table S2.
Mentions: By using the String 10.05 (Search Tool for the Retrieval of Interacting Genes/Proteins) (Szklarczyk et al., 2015) and Cytoscape visualization (Shannon et al., 2003), we constructed PPI networks for DP kinases/phosphatases and all the BR induced DP proteins, respectively. Figure 4A depicted the sub-networks of DP kinases/phosphatases with high confidence score of 0.9. Eight PP2A phosphatases formed 11 edges (interaction relationships) sub-network, of which PP2A-2 (LOC_Os03g59060) and PP2Ac-4 (LOC_Os10g27050) were in the center. In Arabidopsis BR signaling, PP2As are critical phosphatases to dephosphorylate BZR1 and BZR2, which helps to retain the functional BZR1 and BZR2 in the nucleus and confer plants with BR response. The DP pattern suggested critical roles of these PP2As in BR response, whereas the predicted interaction relationships implied that PP2As may work in forms of protein complexes in BR signaling. A CDKG-2-CDKF-1-R2-SNT7 pathway was revealed in our PPI analysis. CDKG-2 (LOC_Os04g41100), CDKF-1 (LOC_Os06g22820), and R2 (LOC_Os05g32600) are cycling-dependent kinases functioning in cell proliferations, indicating this to be a key pathway in BR-regulated cell proliferation. In addition, we also detected a putative OsMEK1-MA3K.14-SMG1 pathway which is related to rice cell proliferation as well as stress resistance (Figure 4A). The full set of 1,821 DP proteins produced an interactome map composed of 459 nodes (proteins) and 946 edges. The various PPI sub-networks are associated with cellulose biosynthesis (Figure 4B), oxidation-reduction reactions (Figure 4C), phytohormone signaling (Figure 4D), and vascular ATP synthesis/transportation (Figure 4E).

View Article: PubMed Central - PubMed

ABSTRACT

The group of polyhydroxysteroid phytohormones referred to as the brassinosteroids (BRs) is known to act on plant development and the stress response. BR signal transduction relies largely on protein phosphorylation. By employing a label-free, MS (Mass Spectrometry)-based phosphoproteomic approach, we report here the largest profiling of 4,034 phosphosites on 1,900 phosphoproteins from rice young seedlings and their dynamic response to BR. 1,821 proteins, including kinases, transcription factors and core components of BR and other hormone signaling pathways, were found to be differentially phosphorylated during the BR treatment. A Western blot analysis verified the differential phosphorylation of five of these proteins, implying that the MS-based phosphoproteomic data were robust. It is proposed that the dephosphorylation of gibberellin (GA) signaling components could represent an important mechanism for the BR-regulated antagonism to GA, and that BR influences the plant architecture of rice by regulating cellulose synthesis via phosphorylation.

No MeSH data available.