Molecular characterization of the arogenate dehydratase family of Arabidopsis thaliana

苯丙氨酸（Phe）、酪氨酸和色氨酸是仅有的含有芳香环结构的氨基酸。作为氨基酸，它们是生命的基石，因为它们是所有蛋白质的基本单位。因此，它们充当细胞内任何酶促反应的分子和功能骨架。在植物中，这些芳香族氨基酸也是许多次级代谢产物的前体，包括类黄酮、木质素、黑色素、酚和单宁。因此，它们有助于植物的结构支撑，色素沉着，气味形成，保护免受紫外线和捕食者的伤害。芳香酸脱氢酶（Arogenate arsenatases，ADT）是催化苯丙氨酸生物合成的最后一步，是苯丙氨酸合成的关键调控步骤。我们提出了一个详细的分子分析的六个ADT基因和它们的六个相应的蛋白质在拟南芥，一个代表性的模式生物植物。我们预测，有许多相似但不相同的酶允许这种植物调节Phe的合成，以响应其许多用途，并且通过内部和环境线索调节这些酶的活性的能力对植物的茁壮成长和生存能力至关重要。调节是一个高度复杂的过程，需要在许多分子水平上的作用网络。通过了解ADT的调节是如何完成的，我们将提供一个基本的了解，这个ADT家族的各个成员如何有助于提供苯丙氨酸的重要途径。由于Phe是许多次级代谢产物的前体，因此了解ADT在芳香族氨基酸合成中的作用对于基础和应用研究具有深远的意义。例如，如果人们可以普遍提高植物中的Phe水平，这些植物可以用作食物，对人类和动物具有增加的营养价值。或者，通过了解ADT如何调节Phe穿梭进入下游途径，可以使植物具有较低的木质素含量（如果这些植物用于造纸，则很有用），增加某些黄酮类化合物的产量（这可能会增加健康益处，因为黄酮类化合物与抗癌特性有关），或者增加使植物能够防御害虫和作物疾病的成分。

Phenylalanine (Phe), tyrosine and tryptophan are the only amino acids containing an aromatic ring structure. As amino acids they are building blocks of life as they are the basic units for all proteins. Therefore they serve as the molecular and functional backbone of any enzymatic reaction within a cell. In plants these aromatic amino acids also serve as precursors to many secondary metabolites including flavonoids, lignins, melanins, phenols and tannins. As such they contribute to the plant's structural support, pigmentation, scent formation, protection from UV light and predators. Arogenate dehydratases (ADTs) are catalyzing the last step in Phe biosynthesis and represent the key regulatory step for producing Phe. We are proposing a detailed molecular analysis of the six ADT genes and their six corresponding proteins in Arabidopsis, a representative model organism for plants. We predict that having that many similar but not identical enzymes allows this plant to regulate the synthesis of Phe in response to its many uses and that the ability to regulate the activity of these enzymes by internal and environmental cues is essential to the plant's ability to thrive and to survive. Regulation is a highly complex process which requires a network of actions on many molecular levels. By learning how the regulation of ADTs is accomplished, we will provide a fundamental understanding of how the various members of this ADT family contribute to deliver Phe to essential pathways. As Phe serves as a precursor to many secondary metabolites, understanding the role that ADTs play in aromatic amino acid synthesis can have far-reaching significance for basic and applied research. For example, if one can generally increase Phe levels in plants, these plants could be used as food with an increased nutrient value for humans and animals. Alternatively, by knowing how ADTs regulate the shuttling of Phe into downstream pathways one could make plants with lower lignin content (useful if these plants are used for paper production), increase the production of certain flavonoids (this could increase the health benefit as flavonoids have been linked to anti cancer properties), or increase components which give plants the ability to defend themselves against pests and crop diseases.