The Arabidopsis Transcription Factor BRASSINOSTEROID INSENSITIVE1-ETHYL METHANESULFONATE-SUPPRESSOR1 Is a Direct Substrate of MITOGEN-ACTIVATED PROTEIN KINASE6 and Regulates Immunity
The Arabidopsis Transcription Factor BRASSINOSTEROID INSENSITIVE1-ETHYL METHANESULFONATE-SUPPRESSOR1 Is a Direct Substrate of MITOGEN-ACTIVATED PROTEIN KINASE6 and Regulates Immunity
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拟南芥转录因子 BRASSINOSTEROID INSENSITIVE1-ETHYL METHANESULFONATE-SUPPRESSOR1 是丝裂原激活蛋白激酶 6 的直接底物并调节免疫
DOI：
10.1104/pp.114.250985
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发表时间：
2015-03-01
期刊：
影响因子：
7.4
通讯作者：
Zhang, Jie
中科院分区：
文献类型：
--
作者：
Kang, Sining;Yang, Fan;Zhang, Jie
病原相关分子模式（pathogen associated molecular patterns, PAMPs）被植物模式识别受体识别，从而激活PAMPs触发的免疫（PTI）。丝裂原活化蛋白激酶（MAPKs）以及其他细胞质激酶整合上游免疫信号，进而通过不同底物分解PTI信号来调节防御反应。然而，只有少数这些信号激酶的直接底物被确定。在这里，我们发现PAMP感知通过病原体诱导的MAPKs，增强了油菜素类固醇（BR）信号通路中参与的转录因子BES1 （INSENSITIVE1-ETHYL methyl sulfonate - suppressor1）的磷酸化。BES1与丝裂原活化蛋白激酶6 （MPK6）相互作用，并被MPK6磷酸化。bes1功能缺失突变体对丁香假单胞菌pv番茄DC3000的抗性受损。BES1 S286A/S137A双突变（BES1(SSAA)）损害了pamp诱导的磷酸化，并且在BES1突变体中不能恢复细菌抗性，这表明BES1磷酸化在植物免疫中起积极作用。BES1被糖原合成酶激酶3 （GSK3）样激酶BR-insensitive2 （BIN2）磷酸化，后者是BR信号的负调控因子。BR感知抑制BIN2活性，使BES1去磷酸化调控植物发育。然而，BES1（SSAA）并不影响BR介导的植物生长，这表明在PTI和BR信号通路中，BES1磷酸化的调节需要不同的残基。我们的研究确定BES1是PTI信号传导中MPK6的唯一直接底物。这一发现揭示了除了gsk3样激酶介导的BES1磷酸化和F box蛋白介导的BES1降解外，mapk介导的BES1磷酸化是植物细胞信号转导的另一种BES1调节机制。
Pathogen-associated molecular patterns (PAMPs) are recognized by plant pattern recognition receptors to activate PAMP-triggered immunity (PTI). Mitogen-activated protein kinases (MAPKs), as well as other cytoplasmic kinases, integrate upstream immune signals and, in turn, dissect PTI signaling via different substrates to regulate defense responses. However, only a few direct substrates of these signaling kinases have been identified. Here, we show that PAMP perception enhances phosphorylation of BRASSINOSTEROID INSENSITIVE1-ETHYL METHANESULFONATE-SUPPRESSOR1 (BES1), a transcription factor involved in brassinosteroid (BR) signaling pathway, through pathogen-induced MAPKs in Arabidopsis (Arabidopsis thaliana). BES1 interacts with MITOGEN-ACTIVATED PROTEIN KINASE6 (MPK6) and is phosphorylated by MPK6. bes1 loss-of-function mutants display compromised resistance to bacterial pathogen Pseudomonas syringae pv tomato DC3000. BES1 S286A/S137A double mutation (BES1(SSAA)) impairs PAMP-induced phosphorylation and fails to restore bacterial resistance in bes1 mutant, indicating a positive role of BES1 phosphorylation in plant immunity. BES1 is phosphorylated by glycogen synthase kinase3 (GSK3)-like kinase BR-insensitive2 (BIN2), a negative regulator of BR signaling. BR perception inhibits BIN2 activity, allowing dephosphorylation of BES1 to regulate plant development. However, BES1(SSAA) does not affect BR-mediated plant growth, suggesting differential residue requirements for the modulation of BES1 phosphorylation in PTI and BR signaling. Our study identifies BES1 as a unique direct substrate of MPK6 in PTI signaling. This finding reveals MAPK-mediated BES1 phosphorylation as another BES1 modulation mechanism in plant cell signaling, in addition to GSK3-like kinase-mediated BES1 phosphorylation and F box protein-mediated BES1 degradation.