Science2014-06-13 3:51 PM

终于,植物版受体被找到了 Identification of a Plant Receptor for Extracellular ATP

论文摘要 

据一项新的研究报告,长期以来踪迹难寻的植物版本的ATP受体终于被发现了,而且它与动物中的ATP受体有很大的不同。ATP是在所有活的生物体中普遍存在的一种化合物。ATP已知在细胞内充当某种能源,但它在细胞外还有另外一个不太知名的作用:它可协助信号传导--发出对生长和发育重要的信号。植物具有对ATP的特定的反应:其中一种是细胞中钙浓度的增加。然而,要发生这样的反应,ATP必须首先与其受体结合,而科学家们一直无法发现该受体。(相比之下,在动物中的与ATP结合的受体则得到了良好的描述。)如今,Jeongmin Choi及其同事在寻找该植物受体上取得了进步。在对开花植物拟南芥进行研究时,他们对拟南芥的变异株进行了遗传筛检--这些变异株不会在ATP存在时触发预期的钙离子内流。在寻找这些变异株中的使得ATP识别受损的基因时,他们发现了2个基因:dorn1-1 和 dorn1-2。至关重要的是,这些基因编码的受体在结构上与在动物中的ATP受体是不同的。研究人员发现,DORN1——这是表达正常受体的基因——的表达可在受到ATP处理的植物中恢复正常的钙离子内流。而这反过来也可帮助这些植物从其机体损伤中恢复过来。文章的作者提出,DORN1 ——这是长期追寻的植物中的ATP受体—— 对感知细胞外ATP是至关重要的,它可能在植物的抗应激中扮演着各种角色。

Abstract 

Extracellular adenosine 5′-triphosphate (ATP) is an essential signaling molecule that is perceived in mammals by plasma membrane P2-type purinoceptors. Similar ATP receptors do not exist in plants, although extracellular ATP has been shown to play critical roles in plant growth, development, and stress responses. Here, we identify an ATP-insensitive Arabidopsis mutant, dorn1 (Does not Respond to Nucleotides 1), defective in lectin receptor kinase I.9 (Arabidopsis Information Resource accession code At5g60300). DORN1 binds ATP with high affinity (dissociation constant of 45.7 ± 3.1 nanomolar) and is required for ATP-induced calcium response, mitogen-activated protein kinase activation, and gene expression. Ectopic expression of DORN1 increased the plant response to physical wounding. We propose that DORN1 is essential for perception of extracellular ATP and likely plays a variety of roles in plant stress resistance.

Editor's Summary

ATP Receptor in Arabidopsis

As well as its role as an intracellular energy source, extracellular adenosine triphosphate (ATP) has diverse functions as a signaling molecule. ATP receptors have been identified in animal cells, but searches based on structural homology have not identified ATP receptors in plants. Choi et al. (p. 290) have now identified an ATP receptor in the model plant Arabidopsis thaliana by tracking down the cause of mutations that leave mutant plants unresponsive to ATP signals. The receptor identified carries an intracellular kinase domain and an extracellular lectin domain.

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