ABA Signaling in Guard Cells Entails a Dynamic Protein-Protein Interaction Relay from the PYL-RCAR Family Receptors to Ion Channels
ABA Signaling in Guard Cells Entails a Dynamic Protein-Protein Interaction Relay from the PYL-RCAR Family Receptors to Ion Channels
复制标题
DOI：
10.1093/mp/sss078
复制
发表时间：
2013-03-01
期刊：
影响因子：
27.5
通讯作者：
Luan, Sheng
中科院分区：
文献类型：
--
作者：
Lee, Sung Chul;Lim, Chae Woo;Luan, Sheng
植物激素脱落酸(ABA)通过调节保卫细胞中特定的离子通道，作为干旱等环境胁迫的整合因子，触发气孔关闭。我们以前报道过，SLAC1是气孔关闭所需的一个外向阴离子通道，它是通过涉及ABA信号成分的可逆蛋白质磷酸化事件来调节的，这些信号成分包括蛋白磷酸酶2C成员和SnRK2-型激酶(OST1)。在这项研究中，我们将ABA信号通路重构为从PYL/RCAR类型受体到PP2CSnRK2磷酸酶激酶对，再到离子通道SLAC1的蛋白质相互作用继而。ABA受体与PP2C磷酸酶相互作用，抑制PP2C磷酸酶活性，使SnRK2蛋白磷酸化，激活SLAC1通道，减少保卫细胞肿胀和气孔关闭。酵母双杂交和双分子荧光互补分析验证了该途径中各组分之间的相互作用。这些生化分析表明，它们的相互作用伙伴对磷酸酶和激酶的活性进行了修饰。SLAC1通道活性被用作信号通路强度的终点读数，这取决于信号成分的不同组合的存在。利用过量表达其中一种ABA受体的转基因植物进行的进一步研究表明，改变相互作用伙伴的相对水平将改变ABA的敏感性。
Plant hormone abscisic acid (ABA) serves as an integrator of environmental stresses such as drought to trigger stomatal closure by regulating specific ion channels in guard cells. We previously reported that SLAC1, an outward anion channel required for stomatal closure, was regulated via reversible protein phosphorylation events involving ABA signaling components, including protein phosphatase 2C members and a SnRK2-type kinase (OST1). In this study, we reconstituted the ABA signaling pathway as a proteinprotein interaction relay from the PYL/RCAR-type receptors, to the PP2CSnRK2 phosphatasekinase pairs, to the ion channel SLAC1. The ABA receptors interacted with and inhibited PP2C phosphatase activity against the SnRK2-type kinase, releasing active SnRK2 kinase to phosphorylate, and activate the SLAC1 channel, leading to reduced guard cell turgor and stomatal closure. Both yeast two-hybrid and bimolecular fluorescence complementation assays were used to verify the interactions among the components in the pathway. These biochemical assays demonstrated activity modifications of phosphatases and kinases by their interaction partners. The SLAC1 channel activity was used as an endpoint readout for the strength of the signaling pathway, depending on the presence of different combinations of signaling components. Further study using transgenic plants overexpressing one of the ABA receptors demonstrated that changing the relative level of interacting partners would change ABA sensitivity.