Asparagine metabolism and function in nitrogen signalling

种子蛋白质的积累取决于氮对发育中的胚的供应，这影响了碳在不同贮藏产物中的分配。天冬酰胺是氮的主要形式，通常运输到库组织。在叶中，天冬酰胺也在夜间短暂积累，在没有光合作用的情况下，有机酸水平不足以进行氮同化。本提案的目的是实现天冬酰胺代谢的功能和感知的天冬酰胺作为一种代谢物信号在植物中的详细了解。拟议的项目将寻求了解天冬酰胺抑制根伸长的生理和代谢基础，并确定天冬酰胺引起的基因表达变化的信号网络的特征。还将研究通过天冬酰胺生物合成酶天冬酰胺合成酶的磷酸化来控制白天和黑夜周期中的天冬酰胺生物合成。一个综合的方法，包括细胞生物学，分子遗传学，代谢产物分析，酶学和翻译后修饰的表征将被用来解决这些目标。拟议的研究将提高我们对植物氮代谢的理解，并可能导致生物技术策略，以操纵谷物中储存产品的水平或提高作物的氮利用效率。

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 major form of nitrogen commonly transported to sink tissue. In leaf, asparagine is also transiently accumulated at night when, in the absence of photosynthesis, levels of organic acids are insufficient for nitrogen assimilation. The objectives of this proposal are to achieve a detailed understanding of asparagine metabolism and of the function and perception of asparagine as a metabolite signal in plants. The proposed project will seek to understand the physiological and metabolic basis underlying the inhibition of root elongation by asparagine, and to characterize the signalling network determining changes in gene expression elicited by asparagine. Control of asparagine biosynthesis during the day and night cycle by phosphorylation of the asparagine biosynthetic enzyme asparagine synthetase will also be investigated. An integrated approach including cellular biology, molecular genetics, metabolite profiling, enzymology and characterization of post-translational modifications will be used to address these goals. The proposed research should improve our understanding of plant nitrogen metabolism and may lead to biotechnological strategies to manipulate the levels of storage products in grain or to enhance nitrogen use efficiency in crops.