Physiological function of nucleoside / nucleobase transport and catabolism

在人类中，核苷转运体执行不同的功能，特别是通过与嘌呤能受体的相互作用。此外，核苷类似物还用于治疗癌症。在植物中，平衡核苷转运蛋白1(ENT1)的功能被发现对花粉发育、种子萌发和维持总的核苷酸平衡至关重要。我们建议更详细地揭示导致观察到的表型的生理原因。重点将放在ENT1功能在多大程度上参与细胞外ATP信号传递的问题上。出乎意料的是，ENT1的活性被发现与液泡RNA代谢有关。因此，通过分析拟南芥中液泡RNA(含量、RNA性质、输入机制)来突出这一方面。此外，我们实验室还将引进大麦作为液泡RNA代谢的模型系统。拟议工作的其他方面与核苷分解代谢有关。在上一个资助期，可以识别出这一途径中的新蛋白质。其中，胞外核苷水解酶NSH3和胞外型尿嘧啶进口体冥王星目前只被初步分析过。将对这些蛋白质的影响进行更详细的分析，以完成我们对细胞外和细胞内核苷分解代谢的理解。

In humans nucleoside transporters execute diverse functions, inter alia through interaction with purinergic receptors. In addition, nucleoside analogs are used to treat cancer. In plants, Equilibrative Nucleoside Transporter 1 (ENT1) function was found to be critical for pollen development, seed germination and maintaining the overall nucleotide balance. We propose to unravel the physiological reason leading to the observed phenotype in more detail. A focus will be on the question to what extend ENT1 function is involved in extracellular ATP signalling. Unexpectedly, ENT1 activity was found to be connected to vacuolar RNA metabolism. Therefore, this aspect shall be highlighted by analyzing vacuolar RNA (contents, nature of RNA, import mechanism) in Arabidopsis. In addition, Barley will be introduced as model system in our lab with respect to vacuolar RNA metabolism. Further aspects of the proposed work are related to nucleoside catabolism. In the last funding period novel proteins in this pathway could be identified. Among these, the extracellular nucleoside hydrolase NSH3 and the plastidic uracil importer Pluto have so far only been analyzed preliminary. A more detailed analysis of the impact of these proteins will be performed to complete our understanding of extracellular and intracellular nucleoside catabolism.