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，它们是细胞内任何酶促反应的分子和功能支柱。在植物中，这些芳香氨基酸也作为许多次生代谢物的前体，包括黄酮类、木质素、黑色素、酚类和单宁。因此，它们有助于植物的结构支持，色素沉着，气味形成，保护免受紫外线和捕食者的侵害。芳香酸脱水酶（ADTs）是催化苯丙氨酸生物合成的最后一步，是苯丙氨酸生产的关键调控步骤。拟南芥是植物的典型模式生物，我们对拟南芥中的6个ADT基因及其相应的6个蛋白进行了详细的分子分析。我们预测，有这么多相似但不相同的酶可以让这种植物根据其多种用途调节苯丙氨酸的合成，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生长和生存能力至关重要。调控是一个高度复杂的过程，它需要在许多分子水平上的作用网络。通过了解ADT的调控是如何完成的，我们将对ADT家族的各个成员如何将Phe传递到必要途径有一个基本的了解。由于Phe是许多次生代谢物的前体，因此了解ADTs在芳香氨基酸合成中的作用对基础和应用研究具有深远意义。例如，如果可以普遍提高植物中的Phe水平，这些植物就可以作为食物使用，对人类和动物具有更高的营养价值。或者，通过了解ADTs如何调节Phe进入下游途径，人们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，这是有用的），增加某些类黄酮的产生（这可能增加健康益处，因为类黄酮与抗癌特性有关），或增加使植物能够抵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.