Collaborative Research: RNA Processing in Trypanosome Mitochondria

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This project will study a distinctive mechanism of gene expression in ancient single-celled parasites called trypanosomes. In most organisms, RNA is copied from DNA and directs protein synthesis without changes in the code. However, in trypanosomal mitochondria (the ‘powerhouse’ of cells), RNA is edited extensively by addition or removal of specific nucleotides. In their complex life cycle, trypanosomes alternate between two very different hosts: humans (and other animals) and insects, which are the vectors of tranmission. The dramatically different environments that the parasites face in humans and insects demand rapid and large-scale metabolic and physiological changes, including in RNA editing. The crucial question of how the RNA editing mechanism is precisely regulated during parasite development remains unanswered and is the focus of this research. The project will have broad educational impact by providing interdisciplinary training opportunities for postdoctoral, graduate, undergraduate, and high school students, with a focus on groups traditionally underrepresented in the STEM disciplines.This project focuses on Trypanosoma brucei mRNA editing regulation and the key role of the REH2C complex that controls editing fidelity in editosomes. The research can shed new light on a question that has remained a mystery for decades: how is mRNA editing differentially controlled across the T. brucei life-cycle? Objective 1 will test the “partial-editing control” (PEC) model of exploiting partial editing to differentially inhibit mRNA maturation in two developmental forms of T. brucei. A recently developed pipeline for RNA-seq/bioinformatic analysis of edited RNAs will be employed for this purpose. Objective 2 will address the source of substrate specificity in editing, specifically to define the role of a rare DEAH-box helicase cofactor and its individual zinc fingers in the mechanism. Objective 3 will examine dynamic interactions of editing components and remodeling by the REH2C complex by elucidating the general organization of editosomes using genetic, biochemical (proximity labeling), and chemical (crosslinking-mass spectrometry) approaches. Overall, these studies will reveal new aspects of editing regulation in two life-cycle stages of the parasite, including editing fidelity, substrate specificity determinants, and editosome interactions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.