RNA Processing in Trypanosome Mitochondria

智力优势：锥虫是动质体原生动物，它包含一种独特的线粒体基因组，称为动泡体(KDNA)。当kDNA中的基因表达时，在数百个小引导RNA(GRNA)的指导下，合成的相应信使RNA被广泛编辑。该项目涉及这些gRNA的成熟。前体RNA分子被合成，其中包括多个gRNA，这些前体在编辑之前被未知的机制和酶处理。本研究鉴定了一种名为mRPN1(线粒体RNA前体加工内切酶1)的新型酶，该酶是布鲁氏锥虫gRNA高效生物合成所必需的。MRPN1切割双链RNA，其特异性使人想起细菌RNaseIII和真核生物DICER，它形成一个由三个蛋白质亚基组成的复合体，这被认为有助于gRNA进入RNA编辑途径。将调查mRPN1及其相关亚单位在mRPN1复合体中的作用。由于gRNA的生物发生实际上是锥虫RNA生物学中一个未被探索的领域，这些研究应该会在早期发散的动质体中开辟新的问题和潜在的新范式。更广泛的影响：这项研究涉及德克萨斯农工大学和其他机构的一个强大的合作者团队，其教育部分直接影响到一名少数民族研究生、博士后研究员和本科生。这些发现将通过在主要研究期刊上发表数据以及在当地和国际会议上向科学界传达。2011年春季，在戈登RNA编辑研究会议和动质体分子细胞生物学会议上，报道了mRPN1的发现及其参与gRNA生物发生的情况。

Intellectual merit: Trypanosomes are kinetoplastid protozoa that contain a unique mitochondrial genome known as the kinetoplast (kDNA). When genes within the kDNA are expressed, the corresponding messenger RNAs that are synthesized are extensively edited in reactions directed by hundreds of small guide RNAs (gRNAs). This project concerns the maturation of these gRNAs. Precursor RNA molecules are synthesized that include multiple gRNAs, and these precursors are processed by unknown mechanisms and enzymes that precede editing. This research characterizes a novel enzyme termed mRPN1 (mitochondrial RNA precursor-processing endonuclease 1), which is required for efficient gRNA biogenesis in Trypanosoma brucei. mRPN1 cleaves double-stranded RNA with a specificity that is reminiscent of bacterial RNase III and eukaryotic Dicer, and it forms a complex with three protein subunits, which is thought to facilitate entry of gRNA into the RNA editing pathway. The role of mRPN1 and its associated subunits in the mRPN1 complex will be investigated. Since gRNA biogenesis is virtually an unexplored field in trypanosome RNA biology, these studies should open new questions and potentially new paradigms in early divergent kinetoplastids. Broader impacts: This research involves a strong team of collaborators at Texas A&M and other institutions, and its educational component directly impacts a graduate student, who is an ethnic minority, a postdoctoral fellow, and an undergraduate student. The findings will be communicated to the scientific community through the publication of data in prominent research journals, and at local and international meetings. The discovery of mRPN1 and its involvement in gRNA biogenesis was reported in the spring 2011 at both the Gordon Research Conference on RNA editing and the Kinetoplastid Molecular Cell Biology Meeting.