RNA Processing in Trypanosome Mitochondria

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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.