Phosphorylation of A-Type ARR to function as negative regulator of cytokinin signal transduction
Phosphorylation of A-Type ARR to function as negative regulator of cytokinin signal transduction
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DOI：
10.4161/psb.3.5.5375
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发表时间：
2008-01-01
影响因子：
2.9
通讯作者：
Kim, Jungmook
中科院分区：
文献类型：
--
作者：
Kim, Jungmook
植物激素细胞分裂素调节植物生长和发育的各个方面。在拟南芥中，类似于细菌和酵母TCS的多步TCS系统用于细胞分裂素信号传导。在TCS系统中，His传感器激酶通过响应于输出信号在His残基上自磷酸化来感知信号，并且磷酸基团被转移到响应调节剂的接收器结构域中的保守Asp残基。然后反应调节因子调节下游信号传导。细胞分裂素多步TCS系统利用额外的组分，含组氨酸的磷酸转移结构域蛋白（HPT）将磷酸基团从传感激酶转移到细胞核中的反应调节剂。典型的响应调节器分为A型或B型。B型ARR是作为细胞分裂素信号传导的正调节剂的转录激活剂，而大多数A型ARR是细胞分裂素信号传导的负调节剂。组氨酰-天冬氨酰磷酸传递被认为是植物细胞分裂素信号转导所必需的。我们的研究表明，ARR 7，一个A型反应调节因子，负调控细胞分裂素信号在各个方面作为一个转录抑制剂，ARR 7的磷酸化是必需的这些ARR 7调节细胞分裂素的反应。在这里，我提出了潜在的机制，ARRs的磷酸化参与调节细胞分裂素介导的基因表达，主要是基于细菌反应调节剂的生化和结构研究。蛋白质-蛋白质相互作用和DNA结合的研究，使用磷酸化和非磷酸化形式的ARR蛋白与其结构的决定，将提供细胞分裂素反应基因调控的ARRs的分子理解。
The plant hormone cytokinins regulate diverse aspects of plant growth and development. In Arabidopsis, a multi-step TCS system similar to bacterial and yeast TCS is used for cytokinin signaling. In a TCS system, a His sensor kinase perceives the signal by autophosphorylating on a His residue in response to an output signal, and the phosphate group is transferred to a conserved Asp residue in the receiver domain of the response regulator. The response regulator then modulates downstream signaling. Cytokinin multi-step TCS system utilizes an additional component, histidine-containing phosphotransfer domain protein (HPT) to transfer the phosphate group from a sensor kinase to a response regulator in the nucleus. The typical response regulators are classified into either type A or B. The type-B ARRs are transcription activators that act as positive regulators of cytokinin signaling, whereas most of the type-A ARRs are negative regulators of cytokinin signaling. Histidyl-aspartidyl phosphorelays are presumed to be essential for this cytokinin signal transduction in plants. Our studies have shown that ARR7, an A-type response regulator, negatively regulates cytokinin signaling in various aspects by acting as a transcriptional repressor and that the phosphorylation of ARR7 is required for these ARR7-regulated cytokinin-responses. Here I propose potential mechanisms by which the phosphorylation of ARRs is involved in regulating cytokinin-mediated gene expression, mainly based on biochemical and structural studies of bacterial response regulators. Protein-protein interaction and DNA-binding studies using the phosphorylated and the un-phosphorylated forms of the ARR proteins with their structural determination will provide molecular understanding of cytokinin-responsive gene regulation by ARRs.