Title
Assembly defects of human tRNA splicing endonuclease contribute to impaired pre-tRNA processing in pontocerebellar hypoplasia
Author
Samoil Sekulovski, Pascal Devant, Silvia Panizza, Tasos Gogakos, Anda Pitiriciu, Katharina Heitmeier, Ewan Philip Ramsay, Marie Barth, Carla Schmidt, Thomas Tuschl, Frank Baas, Stefan Weitzer, Javier Martinez, Simon Trowitzch
Year
2021
Journal
Nature Communications
Abstract
Introns of human transfer RNA precursors (pre-tRNAs) are excised by the tRNA splicing endonuclease TSEN in complex with the RNA kinase CLP1. Mutations in TSEN/CLP1 occur in patients with pontocerebellar hypoplasia (PCH), however, their role in the disease is unclear. Here, we show that intron excision is catalyzed by tetrameric TSEN assembled from inactive heterodimers independently of CLP1. Splice site recognition involves the mature domain and the anticodon-intron base pair of pre-tRNAs. The 2.1-Å resolution X-ray crystal structure of a TSEN15–34 heterodimer and differential scanning fluorimetry analyses show that PCH mutations cause thermal destabilization. While endonuclease activity in recombinant mutant TSEN is unaltered, we observe assembly defects and reduced pre-tRNA cleavage activity resulting in an imbalanced pre-tRNA pool in PCH patient-derived fibroblasts. Our work defines the molecular principles of intron excision in humans and provides evidence that modulation of TSEN stability may contribute to PCH phenotypes.
Full Article
Instrument
LC-2000
Keywords
Intron, RNA, CLP1, TSEN