Monomerization of abscisic acid receptors through CARKs-mediated phosphorylation
Monomerization of abscisic acid receptors through CARKs-mediated phosphorylation
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通过 CARKs 介导的磷酸化实现脱落酸受体的单体化
DOI：
10.1111/nph.18149
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发表时间：
2022-04-27
期刊：
影响因子：
9.4
通讯作者：
Yang, Yi
中科院分区：
文献类型：
--
作者：
Li, Xiaoyi;Xie, Yiting;Yang, Yi
细胞溶质阿坝受体激酶（CARKs）在脱水应答的脱落酸（阿坝）依赖性信号通路中起着关键作用，但其在阿坝信号通路中的调控机制尚不清楚。在本研究中，我们发现卡克家族的CARK 4/5与阿坝受体（RCAR/PYR 1/PYL）相互作用，包括RCAR 3、RCAR 11-RCAR 14，而CARK 2/7/11仅与RCAR 11-RCAR 14相互作用，而不与RCAR 3相互作用。表明卡克激酶家族成员在阿坝信号转导中具有冗余和差异的功能。RCAR 12在体内外均可与RCAR 3形成异源二聚体。此外，卡克家族的成员可以以激酶活性依赖的方式形成同源二聚体或异源二聚体。ITC（等温滴定量热法）分析表明，CARK 1对RCAR 12的磷酸化增强了阿坝结合亲和力。在转cark 157：RCAR 12（T105 D）基因的植株中，模拟磷酸酶RCAR 12（T105 D）表现出ABA诱导的对阿坝不敏感的磷酸酶ABI 1（阿坝insensitive 1）活性的抑制作用，从而导致ABA反应基因RD 29 A和RD 29 B的表达上调。转录因子ABI 5（阿坝不敏感5）通过与CARK 1和CARK 3启动子的ABA反应元件（ABRE）结合来激活CARK 1和CARK 3的转录。总的来说，我们的数据表明，二聚体的CARKs磷酸化同源二聚体或异源二聚体阿坝受体，导致单体化触发阿坝反应在拟南芥。
Cytosolic ABA Receptor Kinases (CARKs) play a pivotal role in abscisic acid (ABA)-dependent pathway in response to dehydration, but their regulatory mechanism in ABA signaling remains unexplored. In this study, we showed that CARK4/5 of CARK family physically interacted with ABA receptors (RCARs/PYR1/PYLs), including RCAR3, RCAR11-RCAR14, while CARK2/7/11 only interacted with RCAR11-RCAR14, but not RCAR3. It indicates that the members in CARK family function redundantly and differentially in ABA signaling. RCAR12 can form heterodimer with RCAR3 in vitro and in vivo. Moreover, the members of CARK family can form homodimer or heterodimer in a kinase activity dependent manner. ITC (isothermal titration calorimetry) analysis demonstrated that the phosphorylation of RCAR12 by CARK1 enhanced the ABA binding affinity. The phosphor-mimic RCAR12(T105D) significantly displayed ABA-induced inhibition of the phosphatase ABI1 (ABA insensitive 1) activity, leading to upregulation of ABA-responsive genes RD29A and RD29B in cark157:RCAR12(T105D) transgenic plants, which exhibited ABA hypersensitive phenotype. The transcription factor ABI5 (ABA insensitive 5) activates the transcriptions of CARK1 and CARK3 by binding to ABA-response elements (ABREs) of their promoters. Collectively, our data imply that the dimeric CARKs phosphorylate homodimer or heterodimer ABA receptors, leading to monomerization for triggering ABA responses in Arabidopsis.