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Talk by Simon Trowitzsch

Title: "Dissecting pre-tRNA splicing across scales - from molecules to disease"
Occasion: SFB - Seminar
Start: 22.05.2025 4:15 pm
Location: CellNanOs, 38/201

About the speaker: Dr. Simon Trowitzsch conducts research at the Institute for Biochemistry, Goethe-University, Frankfurt am Main

Transfer RNAs (tRNAs) play a central role in translating genetic information, ensuring the accurate decoding of messenger RNA into functional proteins. In eukaryotes, a subset of tRNAs requires the precise removal of intervening sequences during maturation. This process is catalyzed by the tRNA splicing endonuclease (TSEN) complex, which excises introns from precursor tRNAs (pre-tRNAs), and a tRNA splicing ligase (TSL) complex, which ligates the resulting exons. Mutations in TSEN and its associated RNA kinase, CLP1, have been linked to pontocerebellar hypoplasia (PCH) — a heterogeneous group of neurodegenerative disorders characterized by underdevelopment of specific brain regions, microcephaly, severe motor disabilities, and early childhood mortality. Despite its fundamental importance, the molecular principles governing human pre-tRNA splicing and its connection to PCH remain poorly understood. Our recent work has addressed this by reconstituting human pre-tRNA splicing in vitro. Through a combination of biophysical and biochemical assays, X-ray crystallography, and single-particle cryo-electron microscopy, we elucidated how human TSEN recognizes the mature body of pre-tRNAs and precisely positions the splice sites for cleavage. Notably, we uncovered a structural and functional asymmetry between the two splice sites, with distinct molecular environments guiding catalysis. Beyond these mechanistic insights, our studies have direct implications for understanding PCH. Using an integrative approach that combines structural and functional data, we demonstrated that PCH-associated mutations destabilize TSEN and impair its interaction with CLP1, providing a molecular explanation for the resulting cellular defects. Future work will aim to elucidate how the various steps of tRNA splicing are coordinated spatially and temporally within the cellular environment.