From the ‡Center for Desert Agriculture, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
§Institute of Plant Sciences Paris-Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France.
Mol Cell Proteomics. 2018 Jan;17(1):61-80. doi: 10.1074/mcp.RA117.000135. Epub 2017 Nov 22.
In Arabidopsis, mitogen-activated protein kinases MPK3, MPK4, and MPK6 constitute essential relays for a variety of functions including cell division, development and innate immunity. Although some substrates of MPK3, MPK4 and MPK6 have been identified, the picture is still far from complete. To identify substrates of these MAPKs likely involved in cell division, growth and development we compared the phosphoproteomes of wild-type and , , and To study the function of these MAPKs in innate immunity, we analyzed their phosphoproteomes following microbe-associated molecular pattern (MAMP) treatment. Partially overlapping substrates were retrieved for all three MAPKs, showing target specificity to one, two or all three MAPKs in different biological processes. More precisely, our results illustrate the fact that the entity to be defined as a specific or a shared substrate for MAPKs is not a phosphoprotein but a particular (S/T)P phosphorylation site in a given protein. One hundred fifty-two peptides were identified to be differentially phosphorylated in response to MAMP treatment and/or when compared between genotypes and 70 of them could be classified as putative MAPK targets. Biochemical analysis of a number of putative MAPK substrates by phosphorylation and interaction assays confirmed the global phosphoproteome approach. Our study also expands the set of MAPK substrates to involve other protein kinases, including calcium-dependent (CDPK) and sugar nonfermenting (SnRK) protein kinases.
在拟南芥中，丝裂原活化蛋白激酶 MPK3、MPK4 和 MPK6 构成了多种功能的必需中继，包括细胞分裂、发育和先天免疫。尽管已经鉴定出了 MPK3、MPK4 和 MPK6 的一些底物，但情况仍远未完全清楚。为了鉴定可能参与细胞分裂、生长和发育的这些 MAPK 的底物，我们比较了野生型和 、 、和 的磷酸蛋白质组。为了研究这些 MAPK 在先天免疫中的功能，我们分析了它们在微生物相关分子模式（MAMP）处理后的磷酸蛋白质组。对于所有三种 MAPK，都检索到了部分重叠的底物，表明在不同的生物学过程中，这些底物对一种、两种或三种 MAPK 具有靶向特异性。更确切地说，我们的结果说明了这样一个事实，即被定义为 MAPK 特定或共享底物的实体不是磷酸蛋白，而是给定蛋白质中特定的（S/T）P 磷酸化位点。有 152 个肽被鉴定为对 MAMP 处理和/或在基因型之间比较时有差异磷酸化，其中 70 个可以归类为推定的 MAPK 靶标。通过磷酸化和相互作用分析对一些推定的 MAPK 底物的生化分析证实了全磷酸蛋白质组方法。我们的研究还将 MAPK 底物的范围扩大到涉及其他蛋白激酶，包括钙依赖性（CDPK）和糖非发酵（SnRK）蛋白激酶。
