Arogenate dehydratases: enzymes and beyond

苯丙氨酸（Phe）是仅有的三种含有芳香环的氨基酸之一。像其他氨基酸一样，苯丙氨酸是生命的基石，因为它是所有蛋白质的基本单位。在植物中，Phe还作为次生或专门代谢物的前体，包括类黄酮、木质素、酚类和单宁。这些特殊的代谢物对植物是必不可少的，因为它们需要结构支持，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家族的各种成员如何促进植物的生存有一个基本的了解。由于Phe是许多特化代谢物的前体，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的意义。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，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，则有用），增加类黄酮水平（这些植物将具有健康益处，因为类黄酮具有许多有益特性，包括抗癌特性）********

Phenylalanine (Phe), is one of only three amino acids that contain an aromatic ring. Phe, like other amino acids, is a building block of life as it is a basic unit for all proteins. In plants Phe also serves as a precursor to secondary or specialized metabolites including flavonoids, lignins, phenols and tannins. These specialized metabolites are essential for plants as they are required for structural support, pigmentation, scent formation, protection from UV light and predators. Arogenate dehydratases (ADTs) are catalyzing the last step in Phe biosynthesis and represent a 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 the plant's survival. As Phe serves as a precursor to many specialized 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 channeling of Phe into downstream pathways one can make plants with lower lignin content (useful if these plants are used for paper production), with increased flavonoid levels (these plants will have health benefits as flavonoids have been many beneficial properties including to anti cancer properties).********