Activation of SnRK2 by Raf-like kinase ARK represents a primary mechanism of ABA and abiotic stress responses
Activation of SnRK2 by Raf-like kinase ARK represents a primary mechanism of ABA and abiotic stress responses
复制标题
DOI：
10.1093/plphys/kiaa046
复制
发表时间：
2021-02-01
期刊：
影响因子：
7.4
通讯作者：
Takezawa, Daisuke
中科院分区：
文献类型：
--
作者：
Islam, Mousona;Inoue, Takumi;Takezawa, Daisuke
Raf-like蛋白激酶脱落酸（阿坝）和非生物胁迫响应Raf-like激酶（方舟）是藓类立碗藓（Physcomitrella）中脱落酸（阿坝）和非生物胁迫响应的关键调节因子。然而，阿坝和非生物胁迫激活方舟调节SnRK 2的潜在机制，包括阿坝受体相关的A组PP 2C（PP 2C-A）的作用尚不清楚。我们确定Ser 1029是方舟激活环中的磷酸化位点，这为ARK的活性调节提供了一种可能的机制。对表达具有Ser 1029-to-Ala突变的ARK-GFP的转基因小球藻方舟系的分析表明，这种替换导致ABA诱导的基因表达、胁迫耐受性和SnRK 2活性的降低。使用抗磷酸肽抗体的免疫印迹分析表明，阿坝治疗迅速刺激野生型（WT）Ser 1029磷酸化。在ABA-超敏ppabil缺乏蛋白磷酸酶2C-A（PP 2C-A）的Ser 1029的磷酸化模式是类似的WT，而很少观察到在ABA-不敏感的方舟错义突变株Ser 1029磷酸化。此外，新分离的ppabi 1方舟线表现出ABA不敏感的表型类似的方舟线。因此，方舟是SnRK 2的主要激活剂，先于PP 2C-A的负调控，这为植物阿坝和非生物胁迫反应提供了原型机制。
The Raf-like protein kinase abscisic acid (ABA) and abiotic stress-responsive Raf-like kinase (ARK) previously identified in the moss Physcomitrium (Physcomitrella) patens acts as an upstream regulator of subgroup III SNF1-related protein kinase2 (SnRK2), the key regulator of ABA and abiotic stress responses. However, the mechanisms underlying activation of ARK by ABA and abiotic stress for the regulation of SnRK2, including the role of ABA receptor-associated group A PP2C (PP2C-A), are not understood. We identified Ser1029 as the phosphorylation site in the activation loop of ARK, which provided a possible mechanism for regulation of its activity. Analysis of transgenic P. patens ark lines expressing ARK-GFP with Ser1029-to-Ala mutation indicated that this replacement causes reductions in ABA-induced gene expression, stress tolerance, and SnRK2 activity. Immunoblot analysis using an anti-phosphopeptide antibody indicated that ABA treatments rapidly stimulate Ser1029 phosphorylation in the wild type (WT). The phosphorylation profile of Ser1029 in ABA-hypersensitive ppabi1 lacking protein phosphatase 2C-A (PP2C-A) was similar to that in the WT, whereas little Ser1029 phosphorylation was observed in ABA-insensitive ark missense mutant lines. Furthermore, newly isolated ppabi1 ark lines showed ABA-insensitive phenotypes similar to those of ark lines. Therefore, ARK is a primary activator of SnRK2, preceding negative regulation by PP2C-A in bryophytes, which provides a prototype mechanism for ABA and abiotic stress responses in plants.