Elucidating Roles of the Haloacid Dehalogenase-Superfamily Phosphatases in Plant Cytosol

所有生物体都需要无机磷酸盐（Pi）作为核酸、磷酸化糖、磷脂和含磷酸盐辅因子的关键组分。Pi也是信号转导级联的参与者，并通过磷酸化调节许多酶的活性。土壤通常含有有限量的可供植物根部吸收的形式的Pi。磷肥已被大规模使用，以应对由于低磷可用性造成的作物生产力有限，但生产这些肥料的原材料预计很快就会耗尽。此外，土壤过度施肥造成了环境破坏。因此，具有提高的磷酸盐利用效率的植物将通过在保护环境的同时实现更高产的农业而造福社会。这项拟议中的研究预计将推进创造这种植物所需的磷酸盐代谢知识。本申请的目的是对拟南芥中的一组磷酸酶进行生物化学表征，并揭示它们在稳态中的作用，稳态是指通过调节生理过程来维持内部平衡的能力。该项目将测试中心假设，即这些酶是细胞溶质磷酸酶，参与调节细胞水平的Pi和有机磷酸酯，以响应植物的发育计划和外部刺激。该项目将通过（1）确定这些酶的生化特性，亚细胞定位和表达模式来验证这一假设;（2）使用遗传方法确定这些酶在植物磷酸盐稳态中的作用。本研究的预期结果是胞质磷酸酶的贡献的整体稳态的Pi和有机磷酸酯，这是一个未经调查的方面在植物中的磷酸盐代谢的知识。这方面的知识预计将有一个显着的影响，对代谢的整体理解的Pi和有机磷酸酯，因为知识的代谢途径上的个别酶如何参与调节细胞内池大小的Pi和有机磷酸酯是特别稀缺，是落后于信号转导网络和转运蛋白的作用。这项研究中获得的知识预计将与未来尝试优化植物组织和器官的磷酸盐使用有关，这将是有益的，因为磷酸盐是施肥过程中添加的限制性营养素，我们预计将在50年内用完用于制造肥料供应的磷矿。减少农业中磷肥的使用也将通过减少污染而有益于环境。参与本项目将为博士后研究助理、研究生和本科生提供植物生物化学、分子生物学和代谢方面的多学科培训机会。一个强有力的努力，将招募代表性不足的群体的成员进入博士后，研究生和本科生的位置。太平洋路德大学是一所以本科生为主的培训机构，该校的一名生物学副教授将参与该项目，并将所获得的新知识应用于更新和发展她所教授的课程，并帮助太平洋路德大学的参与本科生继续在他们的家乡机构进行一些研究，从而使更多的本科生直接受益。

All organisms require inorganic phosphate (Pi) as a key component of nucleic acids, phosphorylated sugars, phospholipids, and phosphate-containing cofactors. Pi is also a participant in signal transduction cascades, and a regulator of many enzyme activities through phosphorylation. Soils generally contain limited amounts of Pi in forms available for uptake by plant roots. Phosphate fertilizers have been used on a mass scale to combat limited crop productivity caused by low Pi availability, but raw materials to produce those fertilizers are expected to soon run out. In addition, over-fertilization of soils has caused environmental damage. Thus, plants with improved phosphate use efficiency would benefit the society by enabling a more productive agriculture while protecting the environment. The proposed study is expected to advance the knowledge of phosphate metabolism, needed to create such plants. The objective of this application is to biochemically characterize a set of phosphatases from Arabidopsis, and to uncover their roles in homeostasis, which refers to the ability to maintain an internal equilibrium by adjusting physiological processes. The project will test the central hypothesis that these enzymes are cytosolic phosphatases that participate in adjusting cellular levels of Pi and organic phosphoesters in response to developmental programs and external stimuli in plants. The project will test this hypothesis by (1) determining biochemical properties, subcellular localization, and expression patterns of these enzymes; and (2) determining the roles of these enzymes in phosphate homeostasis in plants using genetic approaches. The expected outcome of this study is knowledge of the contributions of cytosolic phosphatases to the overall homeostasis of Pi and organic phosphoesters, which is an uninvestigated aspect of phosphate metabolism in plants. This knowledge is expected to have a significant impact on the overall understanding of the metabolism of Pi and organic phosphoesters because the knowledge of how individual enzymes on metabolic pathways participate in regulating intra-cellular pool sizes of Pi and organic phosphoesters is particularly scarce, and is lagging behind that of the roles of signal transduction networks and transporters. The knowledge gained in this study is expected to be relevant to future attempts at optimizing phosphate use by plant tissues and organs, which would be beneficial because phosphate is a limiting nutrient added during fertilization, and we are expected to run out of the phosphate rock used to manufacture the fertilizer supplies in as little as 50 years. Reduced use of phosphate fertilizers in agriculture would also benefit the environment by reducing pollution. Participation in this project will provide an opportunity for multidisciplinary training of postdoctoral research associates, graduate, and undergraduate students in plant biochemistry, molecular biology, and metabolism. A strong effort will be made to recruit members of underrepresented groups into the postdoctoral, graduate, and undergraduate student positions. An Associate Professor of Biology at Pacific Lutheran University, a predominantly undergraduate training institution, will participate in the project and apply the new knowledge gained towards updating and developing courses she teaches, and towards helping the participating undergraduate students from Pacific Lutheran University continue some of their research at their home institution, thus directly benefiting a larger group of undergraduate students.