Carbon and amino acids reciprocally modulate the expression of glutamine synthetase in arabidopsis
Carbon and amino acids reciprocally modulate the expression of glutamine synthetase in arabidopsis
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DOI：
10.1104/pp.121.1.301
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发表时间：
1999-09-01
期刊：
影响因子：
7.4
通讯作者：
Coruzzi, GM
中科院分区：
文献类型：
--
作者：
Oliveira, IC;Coruzzi, GM
在细菌和酵母中，谷氨酰胺合成酶（CS）的表达在转录和转录后水平受到细胞代谢状态的严格调节。我们讨论了光和代谢线索的相对贡献的GS基因家族（叶绿体CS2和胞质CS 1）在拟南芥中的成员的调节。这些研究表明，显着的诱导叶绿体GS 2的mRNA光介导的光敏色素和蔗糖（Suc）水平的光诱导的变化的一部分。相比之下，光对胞质CS 1 mRNA的适度诱导主要是由碳代谢物水平的变化介导的。CS2和CS 1的mRNA的Suc诱导以时间和剂量依赖性方式发生。在CS酶活性水平上也观察到GS mRNA水平的Sue诱导的变化。与此相反，氨基酸拮抗Suc诱导CS，无论是在mRNA的积累和酶活性的水平。对于CS2，其表达受代谢物调节最显著的基因，我们使用GS 2启动子-β-葡萄糖醛酸酶融合来证明转录控制参与了这种代谢调节。我们的研究结果表明，GS在植物中的表达的代谢调控是由相对丰富的碳骨架与氨基酸。这将允许根据植物的代谢状态和生物合成需要进行（或不进行）氮同化成谷氨酰胺。这种类型的GS基因调控让人想起细菌中的氮调节系统，并表明细菌和植物中代谢传感和信号传导之间的进化联系。
In bacteria and yeast, glutamine synthetase (CS) expression is tightly regulated by the metabolic status of the cell, both at the transcriptional and posttranscriptional levels. We discuss the relative contributions of light and metabolic cues on the regulation of members of the GS gene family (chloroplastic CS2 and cytosolic CS1) in Arabidopsis. These studies reveal that the dramatic induction of mRNA for chloroplastic GS2 by light is mediated in part by phytochrome and in part by light-induced changes in sucrose (Suc) levels. In contrast, the modest induction of mRNA for cytosolic CS1 by light is primarily mediated by changes in the levels of carbon metabolites. Suc induction of mRNA for CS2 and CS1 occurs in a time- and dose-dependent manner. Sue-induced changes in GS mRNA levels were also observed at the level of CS enzyme activity. In contrast, amino acids were shown to antagonize the Suc induction of CS, both at the level of mRNA accumulation and that of enzyme activity. For CS2, the gene whose expression was the most dramatically regulated by metabolites, we used a GS2 promoter-beta-glucuronidase fusion to demonstrate that transcriptional control is involved in this metabolic regulation. Our results suggest that the metabolic regulation of GS expression in plants is controlled by the relative abundance of carbon skeletons versus amino acids. This would allow nitrogen assimilation into glutamine to proceed (or not) according to the metabolic status and biosynthetic needs of the plant. This type of GS gene regulation is reminiscent of the nitrogen regulatory system in bacteria, and suggests an evolutionary link between metabolic sensing and signaling in bacteria and plants.