Interaction of the WD40 Domain of a Myoinositol Polyphosphate 5-Phosphatase with SnRK1 Links Inositol, Sugar, and Stress Signaling
Interaction of the WD40 Domain of a Myoinositol Polyphosphate 5-Phosphatase with SnRK1 Links Inositol, Sugar, and Stress Signaling
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DOI：
10.1104/pp.108.130575
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发表时间：
2008-12-01
期刊：
影响因子：
7.4
通讯作者：
Erickson, F. Les
中科院分区：
文献类型：
--
作者：
Ananieva, Elitsa A.;Gillaspy, Glenda E.;Erickson, F. Les
在植物中，肌醇信号通路与几种胁迫、发育和生理过程相关，但这些通路的调控在很大程度上是未知的。在我们的努力，以更好地了解在植物肌醇信号通路，我们已经发现，WD 40重复区的肌醇多磷酸5-磷酸酶（5 PTase 13; At 1g 05630）相互作用的蔗糖非发酵-1-相关激酶（SnRK1.1）在酵母双杂交系统和体外。植物SnRK 1蛋白（也称为AKIN 10/11）已被描述为糖，代谢，应激和发育信号的中心整合子。使用5 PTase 13缺陷的突变体，我们表明，5 PTase 13可以作为SnRK 1活性的调节剂，调节不同的营养物质的可用性。具体来说，我们表明，在低营养或低糖条件下，5 PTase 13作为一个积极的调节SnRK 1活性。相反，在严重饥饿条件下，5 PTase 13作为SnRK 1活性的负调节剂。为了描述5 PTase 13和SnRK1.1之间发生的调节相互作用，我们使用了无细胞降解试验，发现在低营养条件下，需要5 PTase 13来减少SnRK1.1靶向蛋白酶体破坏的量。这种调节很可能涉及细胞核内的5 PTase 13-SnRK1.1相互作用，因为5 PTase 13：绿色荧光蛋白定位于细胞核。我们还表明，5 PTase 13功能的丧失导致根生长的营养水平依赖性降低，沿着脱落酸（阿坝）和糖不敏感性。5 ptase 13突变体积累较少的肌醇1，4，5-三磷酸响应糖胁迫，并在ABA调节的基因表达的改变，这两个是一致的肌醇1，4，5-三磷酸在ABA介导的信号传导的已知作用。我们提出，通过与SnRK1.1蛋白形成蛋白质复合物，5 PTase 13起着连接肌醇、糖和应激信号的调节作用。
In plants, myoinositol signaling pathways have been associated with several stress, developmental, and physiological processes, but the regulation of these pathways is largely unknown. In our efforts to better understand myoinositol signaling pathways in plants, we have found that the WD40 repeat region of a myoinositol polyphosphate 5-phosphatase (5PTase13; At1g05630) interacts with the sucrose nonfermenting-1-related kinase (SnRK1.1) in the yeast two-hybrid system and in vitro. Plant SnRK1 proteins (also known as AKIN10/11) have been described as central integrators of sugar, metabolic, stress, and developmental signals. Using mutants defective in 5PTase13, we show that 5PTase13 can act as a regulator of SnRK1 activity and that regulation differs with different nutrient availability. Specifically, we show that under low-nutrient or -sugar conditions, 5PTase13 acts as a positive regulator of SnRK1 activity. In contrast, under severe starvation conditions, 5PTase13 acts as a negative regulator of SnRK1 activity. To delineate the regulatory interaction that occurs between 5PTase13 and SnRK1.1, we used a cell-free degradation assay and found that 5PTase13 is required to reduce the amount of SnRK1.1 targeted for proteasomal destruction under low-nutrient conditions. This regulation most likely involves a 5PTase13-SnRK1.1 interaction within the nucleus, as a 5PTase13: green fluorescent protein was localized to the nucleus. We also show that a loss of function in 5PTase13 leads to nutrient level-dependent reduction of root growth, along with abscisic acid (ABA) and sugar insensitivity. 5ptase13 mutants accumulate less inositol 1,4,5-trisphosphate in response to sugar stress and have alterations in ABA-regulated gene expression, both of which are consistent with the known role of inositol 1,4,5-trisphosphate in ABA-mediated signaling. We propose that by forming a protein complex with SnRK1.1 protein, 5PTase13 plays a regulatory role linking inositol, sugar, and stress signaling.