Modulation of Abscisic Acid Signaling in Vivo by an Engineered Receptor-Insensitive Protein Phosphatase Type 2C Allele
Modulation of Abscisic Acid Signaling in Vivo by an Engineered Receptor-Insensitive Protein Phosphatase Type 2C Allele
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DOI：
10.1104/pp.110.170894
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发表时间：
2011-05-01
期刊：
影响因子：
7.4
通讯作者：
Marquez, Jose A.
中科院分区：
文献类型：
--
作者：
Dupeux, Florine;Antoni, Regina;Marquez, Jose A.
植物激素脱落酸（ABA）在控制胁迫反应和调节植物生长发育中起着至关重要的作用。 ABA 与 PYRABACTIN RESISTANCE1 (PYR1)/PYR1-LIKE (PYL)/ABA 受体细胞内受体调节成分的结合可抑制 ABA 信号转导的关键负调节因子，即 clade A 蛋白磷酸酶 2C 型 (PP2Cs)，例如 ABA-INSENSITIVE1 和 ABA1 HYPERSENSITIVE （HAB1），导致激活 ABA 信号通路。为了进一步了解激素感知、PP2C 抑制的机制及其对 ABA 信号传导的影响，我们对 PYR1-ABA-HAB1 复合物进行了结构和功能分析。基于结构数据，我们在磷酸酶 hab1(W385A) 的一个关键残基中产生了功能获得性突变，该突变消除了 ABA 依赖性受体介导的 PP2C 抑制，而不损害基础 PP2C 活性。结果，与受体敏感的HAB1相比，即使在ABA和PYR/PYL蛋白存在的情况下，hab1(W385A)也会引起蛋白激酶OST1的组成性失活，因此hab1(W385A)符合超态突变的资格。 hab1(W385A) 在拟南芥 (Arabidopsis thaliana) 植物中的表达导致强烈的显性 ABA 不敏感性，这表明该保守的色氨酸残基可以作为显性进化枝 A PP2C 等位基因生成的靶标。此外，我们的数据强调了色氨酸385等效残基介导的分子相互作用对于体内进化枝A PP2C功能以及ABA感知和信号传导机制的关键作用。
The plant hormone abscisic acid (ABA) plays a crucial role in the control of the stress response and the regulation of plant growth and development. ABA binding to PYRABACTIN RESISTANCE1 (PYR1)/PYR1-LIKE (PYL)/REGULATORY COMPONENTS OF ABA RECEPTORS intracellular receptors leads to inhibition of key negative regulators of ABA signaling, i.e. clade A protein phosphatases type 2C (PP2Cs) such as ABA-INSENSITIVE1 and HYPERSENSITIVE TO ABA1 (HAB1), causing the activation of the ABA signaling pathway. To gain further understanding on the mechanism of hormone perception, PP2C inhibition, and its implications for ABA signaling, we have performed a structural and functional analysis of the PYR1-ABA-HAB1 complex. Based on structural data, we generated a gain-of-function mutation in a critical residue of the phosphatase, hab1(W385A), which abolished ABA-dependent receptor-mediated PP2C inhibition without impairing basal PP2C activity. As a result, hab1(W385A) caused constitutive inactivation of the protein kinase OST1 even in the presence of ABA and PYR/PYL proteins, in contrast to the receptor-sensitive HAB1, and therefore hab1(W385A) qualifies as a hypermorphic mutation. Expression of hab1(W385A) in Arabidopsis (Arabidopsis thaliana) plants leads to a strong, dominant ABA insensitivity, which demonstrates that this conserved tryptophan residue can be targeted for the generation of dominant clade A PP2C alleles. Moreover, our data highlight the critical role of molecular interactions mediated by tryptophan-385 equivalent residues for clade A PP2C function in vivo and the mechanism of ABA perception and signaling.