Plant dicarboxylic acid homeostasis: on the specific physiological role of enzymes involved in malate decarboxylation

苹果酸是C3代谢的重要中间体，是三羧酸和乙醛酸循环的组成部分，参与气孔运动，控制胞质pH，维持细胞电平衡，是一种重要的固定碳形式。苹果酸盐在所有细胞区室中都存在并发生转化，这是因为参与其合成或去除的酶和特定的膜载体无处不在。这一建议，这是基于我们最近发表的工作，旨在阐明苹果酸在拟南芥中稳态的几个方面，特别侧重于阐明苹果酸脱羧酶（NADP-ME）的生物学功能。计划中的工作包括由于特定细胞类型或亚细胞区室中缺乏或过度表达NAD-和NADP-ME活性而改变苹果酸盐和富马酸盐含量的转基因植物的产生和表征。将通过结合代谢通量测量、代谢谱、蛋白质组学分析和转录组学分析来评估对C和n代谢的影响，研究特定活性的过表达或缺乏表达对代谢通量重定向的影响。不同方法的综合结果有望为植物二羧酸代谢提供新的思路。

Malate is an important intermediate in C3 metabolism as a component of the tricarboxylic acid and the glyoxylate cycles, it participates in stomatal movements, in the control of cytosolic pH, the maintenance of the cell electrical balance and is an important form of fixed carbon. Malate is present and undergoes transformations in all cell compartments due to the ubiquitous presence of enzymes involved in its synthesis or removal and of specific membrane carriers. This proposal, which is based on our recently published work, was designed to clarify several aspects of malate homeostasis in Arabidopsis thaliana with special focus on the elucidation of the biological function of malate decarboxylating enzymes (NAD-and NADP-ME). The planned work involves the generation and characterization of transgenic plants with altered malate and fumarate contents due to the lack or overexpression of NAD- and NADP-ME activities in specific cellular types or subcellular compartments. The effects of the overexpression or the lack of expression of a determined activity on the redirection of metabolic fluxes will be investigated by combining the measurement of metabolic fluxes with metabolic profiling, proteomic analysis and transcriptome analysis to assess the impact on C- and N-metabolism. The combined results of the different approaches are expected to shed new light on plant dicarboxylic acid metabolism.