AGF1, an AT-hook protein, is necessary for the negative feedback of AtGA3ox1 encoding GA 3-oxidase
AGF1, an AT-hook protein, is necessary for the negative feedback of AtGA3ox1 encoding GA 3-oxidase
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DOI：
10.1104/pp.106.093542
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发表时间：
2007-03-01
期刊：
影响因子：
7.4
通讯作者：
Takahashi, Yohsuke
中科院分区：
文献类型：
--
作者：
Matsushita, Akane;Furumoto, Tsuyoshi;Takahashi, Yohsuke
负反馈是生物体将内部环境维持在可容忍范围内的一种基本机制。赤霉素(GAs)是植物生长发育的重要调节因子，包括种子萌发、茎伸长和开花。植物体内GA的生物合成受反馈机制的调控。GA_3-氧化酶(GA3ox)催化生物合成途径的最后一步，以产生生理活性气体。在此，我们发现在拟南芥AtGA3ox家族中，只有AtGA3ox1受GA负反馈的调控。我们利用转基因植物鉴定了一个负责AtGA3ox1的GA负反馈的顺式作用序列。此外，我们还鉴定了一个AT-挂钩蛋白AGF1(GA反馈调节的AT-挂钩蛋白)，它是GA负反馈顺式作用序列的DNA结合蛋白。顺式作用序列中的突变取消了GA负反馈和AGF1结合。此外，在拟南芥中，AGF1的结构性表达影响GA负反馈。我们的结果表明，AGF1通过与AtGA3ox1的GA负反馈的顺式作用序列结合，在GAS的动态平衡中发挥作用。
Negative feedback is a fundamental mechanism of organisms to maintain the internal environment within tolerable limits. Gibberellins (GAs) are essential regulators of many aspects of plant development, including seed germination, stem elongation, and flowering. GA biosynthesis is regulated by the feedback mechanism in plants. GA 3-oxidase (GA3ox) catalyzes the final step of the biosynthetic pathway to produce the physiologically active GAs. Here, we found that only the AtGA3ox1 among the AtGA3ox family of Arabidopsis (Arabidopsis thaliana) is under the regulation of GA-negative feedback. We have identified a cis-acting sequence responsible for the GA-negative feedback of AtGA3ox1 using transgenic plants. Furthermore, we have identified an AT-hook protein, AGF1 (for the AT-hook protein of GA feedback regulation), as a DNA-binding protein for the cis-acting sequence of GA-negative feedback. The mutation in the cis-acting sequence abolished both GA-negative feedback and AGF1 binding. In addition, constitutive expression of AGF1 affected GA-negative feedback in Arabidopsis. Our results suggest that AGF1 plays a role in the homeostasis of GAs through binding to the cis-acting sequence of the GA-negative feedback of AtGA3ox1.