Inorganic polyphosphate in eukaryotes - synthesis, detection, metabolism and physiology

无机多聚磷酸盐（polyP）是由数十至数百个磷酸盐残基通过高能磷酸酐键连接而成的生物聚合物。这种普遍存在的益生元聚合物的代谢和功能在原核生物和酵母中已经被很好地理解。虽然存在于多细胞真核生物中的水平要低得多，但聚P与重要的生理现象有关，如哺乳动物的血液凝固和骨钙化。虽然一些研究已经暗示polyP参与不同的细胞功能，包括线粒体稳态、TOR信号传导、伴侣蛋白功能和神经元信号传导，但对高等真核生物中polyP生物学的总体理解仍然很差。其主要原因是缺乏检测和定量聚P的特异性和敏感性方法，并且负责多细胞动物中聚P合成的酶仍然未知。此外，聚P和类似物的化学合成，这可以帮助识别参与聚P周转的酶，并探测聚P的其他细胞功能，是欠发达的。在DBT和DFG资助印度-德国生命科学基础研究项目的联合项目提案中，我们汇集了我们在生物化学（Rashna Bhandari），化学合成（Henning Bandari）和果蝇遗传学（Manish Jaiswal）方面的互补专业知识，以解决我们对多细胞真核生物中polyP生物学理解的不足。我们将共同努力实现以下目标：a）开发灵敏和特异的检测方法来检测生物样品中的polyP b）化学合成polyP和类似物，并实现此类化合物的细胞递送c）研究肌醇焦磷酸和polyP在线粒体能量代谢中的相互作用d）确定高等真核生物中polyP合成的途径d）研究polyP消耗的生物体水平表型效应整体而言，该提案将帮助我们解开高等真核生物中polyP合成和功能的谜团，并将通过提供新的分析，生化和生物学方法显着推动该领域。

Inorganic polyphosphate (polyP) is biopolymer of tens to hundreds of phosphate residues linked by a high-energy phosphoanhydride bonds. The metabolism and functions of this prebiotic ubiquitous polymer are quite well understood in prokaryotes and yeast. Although present in multicellular eukaryotes at much lower levels, polyP has been linked to important physiological phenomena such as blood clotting and bone calcification in mammals. While some studies have implicated polyP in different cellular functions including mitochondrial homeostasis, TOR signaling, chaperone function, and neuronal signaling, the overall understanding of polyP biology in high eukaryotes remains poor. The main reasons for this are the lack of specific and sensitive methods for the detection and quantification of polyP, and that the enzyme(s) responsible for polyP synthesis in metazoans is still unknown. Also, the chemical synthesis of polyP and analogues, which can help identify the enzymes involved in polyP turnover, and probe other cellular functions of polyP, is underdeveloped. In this joint project proposal to DBT and DFG for funding Indo-German Fundamental Research Projects in the Life Sciences, we bring together our complementary expertise in Biochemistry (Rashna Bhandari), Chemical Synthesis (Henning Jessen) and Drosophila genetics (Manish Jaiswal) to address the shortcomings in our understanding of polyP biology in multicellular eukaryotes. We will work together to achieve the following objectives:a) Develop sensitive and specific assays to detect polyP in biological samplesb) Chemically synthesize polyP and analogues and achieve the cellular delivery of such compoundsc) Investigate cross-talk between inositol pyrophosphates and polyP in mitochondrial energy metabolismd) Identify the pathway of polyP synthesis in higher eukaryotese) Study organism-level phenotypic effects of polyP depletionIn its entirety, this proposal will help us to unravel the enigmas of polyP synthesis and function in higher eukaryotes and will significantly drive the field by providing novel analytical, biochemical and biological approaches.