Poster abstracts

Poster number 92 submitted by Natalie McAdams

Characterization of two essential components of the trypanosome mitochondrial RNA-binding complex 1, MRB1

Natalie M. McAdams (SUNY Buffalo), Laurie K. Read (SUNY Buffalo)

Abstract:
Kinetoplastid parasites, including Trypanosoma brucei, T. cruzi, and Leishmania spp., are the causative agents of African sleeping sickness, Chagas’ disease, and leishmaniasis in humans, respectively, leading to hundreds of thousands of deaths per year worldwide. Mitochondrial mRNAs in kinetoplastid parasites require extensive remodeling by a unique process termed uridine insertion/deletion RNA editing to create translatable open reading frames. The RNA editing catalytic enzymes are present in a stable multiprotein structure termed the RNA editing core complex (RECC) or 20S editosome. In addition to RECC, a multiprotein complex called the mitochondrial RNA-binding complex 1 (MRB1) in T. brucei is required for efficient RNA editing. We reported the presence of an MRB1 core that contains at least 7 proteins and is essential for RNA editing initiation. We have also identified subcomplexes containing the TbRGG2 RNA binding/annealing protein; known proteins of the TbRGG2 subcomplexes are essential for 3’ to 5’ progression of editing on pan-edited RNAs. Here, we present ongoing studies of two potential TbRGG2 subcomplex proteins, MRB800 and PhyH. RNAi-mediated knockdown of MRB800 or PhyH in insect stage T. brucei leads to a severe growth defect. However, the effects on mRNA levels are different between the two proteins. Depletion of PhyH results in a decrease in only extensively edited transcripts, while removal of MRB800 causes a decrease in all edited transcripts. Both proteins affect the progression of RNA editing within the ATPase 6 transcripts but appear to affect progression at different places along the editing process. In addition, we have begun to characterize the protein-protein interactions exhibited between MRB800, PhyH, and other components of the TbRGG2 subcomplex. These studies provide another piece in the puzzle of our ongoing characterization of the essential and multifunctional RNA editing complex, MRB1.

Keywords: RNA editing , trypanosomes