College of Biological Sciences, China Agricultural University, 100094 Beijing, China.
Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, 100084 Beijing, China.
New Phytol. 2011 Oct;192(1):61-73. doi: 10.1111/j.1469-8137.2011.03793.x. Epub 2011 Jun 21.
• Ca(2+) -dependent protein kinase (CDPK) is believed to be involved in abscisic acid (ABA) signaling, and several members of the Arabidopsis CDPK superfamily have been identified as positive ABA signaling regulators, but it remains unknown if CDPK negatively regulates ABA signaling. • Here, we investigated the function of an Arabidopsis (Arabidopsis thaliana) CDPK, CPK12, in ABA signaling pathway. • We generated Arabidopsis CPK12-RNAi lines, and observed that downregulation of CPK12 resulted in ABA hypersensitivity in seed germination and post-germination growth, and altered expression of a set of ABA-responsive genes. Expression assay showed that CPK12 was ubiquitously expressed and localized to both cytosol and nucleus. Biochemical assays showed that CPK12 interacted with, phosphorylated and stimulated a type 2C protein phosphatase ABI2, and phosphorylated two ABA-responsive transcription factors (ABF1 and ABF4) in vitro. • Our findings show that the Arabidopsis CPK12 is a negative ABA-signaling regulator in seed germination and post-germination growth, suggesting that different members of the CDPK family may constitute a regulation loop by functioning positively and negatively in ABA signal transduction.
钙依赖蛋白激酶（CDPK）被认为参与脱落酸（ABA）信号转导，拟南芥 CDPK 超家族的几个成员已被鉴定为正向 ABA 信号转导调节剂，但 CDPK 是否负向调节 ABA 信号转导仍不清楚。在这里，我们研究了拟南芥（Arabidopsis thaliana）CDPK，CPK12 在 ABA 信号通路中的功能。我们生成了拟南芥 CPK12-RNAi 系，并观察到 CPK12 的下调导致种子萌发和萌发后生长的 ABA 超敏反应，并改变了一组 ABA 响应基因的表达。表达分析表明 CPK12 广泛表达并定位于细胞质和细胞核。生化分析表明 CPK12 在体外与 2C 型蛋白磷酸酶 ABI2 相互作用、磷酸化并刺激其磷酸化，以及 ABA 响应转录因子（ABF1 和 ABF4）。我们的研究结果表明，拟南芥 CPK12 是种子萌发和萌发后生长中 ABA 信号的负调节因子，这表明 CDPK 家族的不同成员可能通过在 ABA 信号转导中正向和负向作用构成一个调节环。
