Asparagine metabolism and function in nitrogen signaling

种子蛋白质的积累依赖于对发育中的胚胎的氮素供应，这影响了碳在不同贮藏产品中的分配。天冬酰胺是高等植物氮素的一种重要运输形式。天冬酰胺酶被认为在向包括发育中的种子在内的下沉组织提供氮的过程中起着关键作用。这种酶将天冬酰胺分解成天冬氨酸和氨，天冬氨酸和氨被重新同化并用于合成其他氨基酸。在大豆和谷类中观察到发育中的种子中游离天冬酰胺水平与成熟时蛋白质含量之间的相关性，这表明天冬酰胺可能作为一种代谢物信号调节蛋白质积累。这项建议的目的是实现对高等植物中天冬酰胺分解代谢的详细了解，以及天冬酰胺作为氮代谢信号的功能和感知。将使用包括酶结构和功能研究、分子遗传学、转录本和代谢物图谱以及代谢生物化学在内的方法来解决这一目标。拟议的研究将提高我们对种子氮素供应过程的理解，并可能导致生物技术策略来操纵贮藏产品的水平，以提高营养价值或用于生物工业应用。

Seed protein accumulation is dependent on the supply of nitrogen to the developing embryo, which influences the partitioning of carbon into the different storage products. Asparagine is a key transport form of nitrogen in higher plants. The enzyme asparaginase is hypothesized to play a critical role in the supply of nitrogen to sink tissues including developing seeds. This enzyme breaks down asparagine into aspartate and ammonia, which is re-assimilated and used in the synthesis of other amino acids. A correlation between free asparagine levels in developing seeds and protein content at maturity has been observed in soybean and cereals, suggesting a possible role of asparagine as a metabolite signal regulating protein accumulation. The objectives of this proposal are to achieve a detailed understanding of asparagine catabolism in higher plants, and of asparagine function and perception as a nitrogen metabolite signal. Approaches including the study of enzyme structure and function, molecular genetics, transcript and metabolite profiling, and metabolic biochemistry will be used to address this goal. The proposed research should improve our understanding of the process of seed nitrogen supply, and may lead to biotechnological strategies to manipulate the levels of storage products, either to enhance nutritional value or for bio-industrial applications.