Chloroplastidäre Ribonukleoproteine (cpRNPs): globale Stabilisatoren chloroplastidärer RNA-Reservoirs während der Stressantwort

叶绿体RNA加工是由许多核编码的RNA结合蛋白介导的。尽管越来越多的知识所涉及的因素和机制问题的个别基因表达步骤正在解决，我们仍然知道很少真正的叶绿体基因表达的调控步骤。我们也不了解叶绿体基因是如何共同调节的，以及叶绿体基因的表达是如何适应不断变化的外部条件的。我们最近证明，叶绿体核糖核蛋白（cpRNP）的影响叶绿体mRNA的积累和加工在全球范围内的低温条件下。未发表的实验进一步证明，cpRNP在翻译应激条件下全面结合从叶绿体核糖体释放的RNA。cpRNP以光和温度依赖性方式表达和磷酸化。总之，cpRNP具有独特的潜力，作为全球性的外部信号调节器对叶绿体RNA库。我们建议处理以下问题：在胁迫驯化过程中，cpRNP和核糖体分别与RNA库结合，它们是如何相互对应的？二.磷酸化是如何影响cpRNP的作用的，连接cpRNP与外部信号的激酶是什么？三. cpRNP如何介导拟南芥的抗寒性？四. cpRNP作用的分子机制是什么，特别是叶绿体mRNA上的确切结合位点是什么？我们将使用全基因组定量分析的RNA配体的cpRNP（RIP-Chip和iCLIP），以确定的作用，cpRNP和他们的已知的磷酸化位点在驯化过程中。此外，我们将确定激酶作用于cpRNP使用遗传和生物化学方法的组合。最后，将利用叶绿体基因表达的药理学、遗传学和生理学扰动来确定在发育和胁迫驯化期间的什么时间cpRNP对叶绿体mRNA提供稳定性是重要的。总之，我们的分析旨在解开，叶绿体RNA代谢是如何控制和执行的cpRNP在全球范围内响应压力相关的叶绿体功能和植物生存。

Chloroplast RNA processing is mediated by a multitude of nuclear-encoded RNA binding proteins. Despite growing knowledge on the factors involved and mechanistic questions of individual gene expression steps being addressed, we still know little about the truly regulatory steps of chloroplast gene expression. Nor do we understand how chloroplast genes are co-regulated and how chloroplast gene expression is acclimated to changing external conditions. We have recently demonstrated that chloroplast ribonucleoproteins (cpRNPs) impact chloroplast mRNA accumulation and processing under low temperature conditions on a global scale. Unpublished experiments furthermore demonstrate that cpRNPs globally bind RNAs freed from chloroplast ribosomes under conditions of translational stress. cpRNPs are expressed and phosphorylated in a light and temperature-dependent manner. Taken together, cpRNPs have the unique potential to act as global modulators of external signals towards chloroplast RNA pools. We propose to address the following questions:I. How do RNA-pools bound by cpRNPs and by ribosomes, respectively, correspond to each other during stress acclimation?II. How does phosphorylation impact the role of cpRNPs and what are the kinases linking cpRNPs to external signals?III. How do cpRNPs mediate cold-resistance in Arabidopsis?IV. What is the molecular mechanism of cpRNP action, in particular, what are the exact binding sites on chloroplast mRNAs?We will use genome-wide quantitative profiling of RNA ligands of cpRNPs (RIP-Chip and iCLIP) to determine the role of cpRNPs and their known phosphorylation sites during acclimation processes. Furthermore, we will identify kinases acting upon cpRNPs using a combination of genetic and biochemical approaches. Finally, pharmacological, genetic and physiological perturbations of chloroplast gene expression will be harnessed to determine, at what time during development and stress acclimation cpRNPs are important to provide stability to chloroplast mRNAs. In sum, our analysis is designed to unravel, how chloroplast RNA metabolism is controlled and executed by cpRNPs on a global scale in response to stressors relevant for chloroplast function and plant survival.