Molecular characterization of the arogenate dehydratase family of Arabidopsis thaliana

苯丙氨酸(Phe)、酪氨酸和色氨酸是唯一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反应的分子和功能骨架。在植物中，这些芳香氨基酸也是许多次生代谢物的前体，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持、色素沉着、气味形成、保护免受紫外线照射和捕食者。芳香酸脱水酶(ADT)是苯丙氨酸生物合成的最后一步催化剂，是苯丙氨酸合成的关键调控步骤。我们建议对拟南芥中的六个ADT基因及其相应的六个蛋白质进行详细的分子分析，拟南芥是植物的典型模式生物。我们预测，拥有如此多相似但不相同的酶使这种植物能够调节Phe的合成，以响应其多种用途，并且通过内部和环境线索调节这些酶的活性的能力对于植物的茁壮成长和生存是必不可少的。调控是一个高度复杂的过程，需要在许多分子水平上的行动网络。通过学习ADT的调控是如何完成的，我们将提供一个基本的理解，这个ADT家族的不同成员如何有助于将Phe传递到必要的途径。由于苯丙氨酸是许多次生代谢物的前体，了解ADTS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，如果人们能够普遍提高植物中的苯丙氨酸水平，这些植物就可以被用作对人类和动物具有更高营养价值的食物。或者，通过了解ADT如何调节Phe的下游途径，人们可以使植物的木质素含量较低(如果这些植物用于造纸是有用的)，增加某些类黄酮类的生产(这可以增加健康益处，因为类黄酮类已经被联系到抗癌特性)，或者增加使植物能够防御病虫害的成分。

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.