Collaborative Research: RNA processing in trypanosome mitochondria

这个项目将研究古代单细胞寄生虫中一种独特的基因表达机制，称为锥虫。与大多数生物不同的是，在锥虫(和其他生物)的产生能量的线粒体中，RNA是通过添加或删除特定信息来编辑的，而大多数生物使用从DNA复制的RNA来指导蛋白质合成。编辑发生的原因尚不清楚，但了解它是如何发生的可能会为这种类型的基因改变的功能提供重要线索。该项目将通过为博士后、研究生、本科生和高中生提供跨学科培训机会，产生广泛的教育影响。此外，还将针对STEM学科中传统上代表性较低的群体的学生进行具体努力。这个项目的重点是锥虫线粒体中的RNA编辑过程。通过一种名为RECC的中央编辑酶的作用，尿苷可以在数十个mRNA的数千个特定位置插入或删除。这一广泛的编辑过程由数百个小的非编码引导RNA指导，并涉及几个辅助因素。然而，编辑调控的机制基础仍然是锥虫RNA生物学中的一个长期存在的问题。在之前的工作中，人们发现了一个名为REH2 C的调控编辑亚复合体，并发现它含有三个蛋白质亚基。其中两个，一个解旋酶和一个锌指蛋白，似乎直接参与编辑。将结合遗传学、生化、生物信息学和蛋白质组学的方法来研究这些蛋白质如何与mRNAs组装，并在体内将mRNAs引导成编辑体复合体，以及这些复合体如何执行编辑功能。这些研究可能建立RNA编辑调控的新范式。从更广泛的意义上讲，这些研究将让人们更好地理解这一令人惊叹的过程是如何演变的。这个系统可以用来与相关的RNA解旋酶和RNA过程进行类比，这些RNA解旋酶和RNA过程由小引导RNA指导，最近在真核生物谱系中进化。

This project will study a unique mechanism of gene expression in ancient single-celled parasites called trypanosomes. Unlike most organisms that use the RNA copied from DNA "as is" for directing protein synthesis, in the energy-generating mitochondria of trypanosomes (and other organisms), the RNA is edited by addition or removal of specific information. Why editing occurs is not clear, but understanding how it happens may provide important clues about the function of this type of genetic alteration. The project will have broad educational impact by providing interdisciplinary training opportunities for postdoctoral, graduate, undergraduate, and high school students. In addition, specific efforts will target students from groups traditionally underrepresented in the STEM disciplines. This project focuses on the process of RNA editing in the mitochondria of trypanosomes. Through the action of a central editing enzyme, called RECC, uridylates are inserted or deleted at thousands of specific sites in dozens of mRNAs. This extensive editing process is directed by hundreds of small non-coding guide RNAs and involves several auxiliary factors. However, the mechanistic basis of the regulation of editing remains a long-standing question in trypanosomal RNA biology. In previous work, a regulatory editing subcomplex, called REH2C, was identified and found to contain three protein subunits. Two of these, a helicase and a zinc-finger protein, appear to participate directly in editing. A combination of genetic, biochemical, bioinformatics, and proteomic approaches will be used to address how these proteins assemble with mRNAs and guide mRNAs into editosome complexes in vivo and how the complexes carry out editing functions. These studies may establish new paradigms in RNA editing regulation. In a broader sense, the studies will allow a better understanding of how this amazing process evolved. This system can be used to draw analogies with related RNA helicases and RNA processes that are directed by small guide RNAs and that evolved more recently in eukaryotic lineages.