Metabolic adaptation of phosphate-starved plants - Functional analyses of novel-type, intracellular phosphatases of the the HAD superfamily

磷的有效性对植物的代谢和生产力有着深远的影响。低无机磷利用率触发代谢反应以维持植物细胞内磷酸盐稳态。植物对外源磷限制的反应是通过严格控制策略来重新安排磷的代谢消耗和再活化途径，并最大限度地从环境中获取磷。本项目致力于功能性植物策略的细胞内磷酸盐动员的新型磷酸酶，属于卤酸脱卤酶（HAD）超家族。相应的基因被Pi饥饿以高度特异性的方式上调。我们最近发现的AtPECP 1和AtPPsPase 1，这是磷酸乙醇胺/磷酸胆碱和焦磷酸特异性磷酸酶，分别的酶的性质，表明在脂质和碳水化合物代谢的功能作用。这是拟议的工作的目标，以阐明基因产物如何有助于驯化反应，低磷可用性。将向酶功能完全受损或增强的拟南芥野生型植物和转基因系提供不同的Pi浓度，并记录生理学、形态学和生物化学响应。将使用基于质谱的方法定量分析脂质降解产物和不同主要中间体（如磷酸化和UDP活化糖）模式的变化。将在突变体互补测定中测试工程化蛋白质的功能性。营养应激诱导的转录变化引发的AtPPsPase 1行动将通过微阵列方法进行研究。定量RT-PCR将用于描绘Pi饥饿反应的调节因子的影响。AtPECP 1和ATPPsPase 1通过启动子驱动的报告基因的时空表达是针对测试PI依赖的源-库关系。

The availability of phosphorus (P) has a profound impact on plant metabolism and productivity. Low inorganic phosphate availability triggers metabolic responses to maintain intracellular phosphate homeostasis in plants. Plants respond to exogenous P limitation with tightly controlled strategies to reprioritize metabolic phosphate consumption and remobilization pathways and to maximize the acquisition from the environment. This project is dedicated to functional plant strategies of intracellular phosphate mobilization by novel-type phosphatases which belong to the Haloacid Dehalogenase (HAD) superfamily. The respective genes are up-regulated by Pi starvation in a highly specific manner. Our recent discovery of the enzymatic properties of AtPECP1 and AtPPsPase1 which are phosphoethanolamine/phosphocholine and pyrophosphate-specific phosphatases, respectively, suggests functional roles in lipid and carbohydrate metabolism. It is the goal of the proposed work to elucidate how the gene products contribute to acclimatory responses to low P availability. Arabidopsis wild-type plants and transgenic lines completely compromised or enhanced in enzyme function will be supplied with different Pi concentrations and physiological, morphological and biochemical responses will be recorded. Changes in the pattern of lipid degradation products and distinct primary intermediates such as phosphorylated and UDP-activated sugars will be analyzed quantitatively using methods based on mass spectrometry. The engineered proteins will be tested for functionality in mutant complementation assays. Nutritional stress-induced transcriptional changes triggered by AtPPsPase1 action will be investigated by a microarray approach. Quantitative RT-PCR will be used to delineate the impact of regulatory factors of the Pi starvation response. The spatio-temporal expression of AtPECP1 and ATPPsPase1 by promoter-driven reporter genes are directed at testing Pi-dependent source-sink-relations.