Structural basis of gRNA stabilization and mRNA recognition in trypanosomal RNA editing

• Published in: Science (American Association for the Advancement of Science) 2023-07, Vol.381 (6653), p.eadg4725-eadg4725
• Main Authors: Liu, Shiheng, Wang, Hong, Li, Xiaorun, Zhang, Fan, Lee, Jane K J, Li, Zihang, Yu, Clinton, Hu, Jason J, Zhao, Xiaojing, Suematsu, Takuma, Alvarez-Cabrera, Ana L, Liu, Qiushi, Zhang, Liye, Huang, Lan, Aphasizheva, Inna, Aphasizhev, Ruslan, Zhou, Z Hong
• Format: Article
• Language: English
• Subjects: African trypanosomiasis; Binding sites; Cleavage; Coding; Cryoelectron Microscopy; Dimers; Editing; Electron microscopy; gRNA; Hybridization; Information transfer; Microscopy; Mitochondria; Molecular structure; Nuclease; Nucleotide sequence; Nucleotides; Parasites; Phylogeny; Polypeptides; Protein structure; Proteins; Protozoa; Protozoan Proteins - genetics; Protozoan Proteins - metabolism; Recognition; Ribonucleic acid; RNA; RNA Editing; RNA Stability; RNA triphosphatase; RNA, Guide, Kinetoplastida - chemistry; RNA, Messenger - chemistry; RNA, Messenger - genetics; RNA, Protozoan - chemistry; RNA, Protozoan - genetics; Secondary structure; Sequestering; Stabilization; Substrates; Transcripts (Written Records); Trypanocides; Trypanosoma brucei; Trypanosoma brucei brucei - genetics; Uridine; Vector-borne diseases
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.adg4725

In , the editosome, composed of RNA-editing substrate-binding complex (RESC) and RNA-editing catalytic complex (RECC), orchestrates guide RNA (gRNA)-programmed editing to recode cryptic mitochondrial transcripts into messenger RNAs (mRNAs). The mechanism of information transfer from gRNA to mRNA is unclear owing to a lack of high-resolution structures for these complexes. With cryo-electron microscopy and functional studies, we have captured gRNA-stabilizing RESC-A and gRNA-mRNA-binding RESC-B and RESC-C particles. RESC-A sequesters gRNA termini, thus promoting hairpin formation and blocking mRNA access. The conversion of RESC-A into RESC-B or -C unfolds gRNA and allows mRNA selection. The ensuing gRNA-mRNA duplex protrudes from RESC-B, likely exposing editing sites to RECC-catalyzed cleavage, uridine insertion or deletion, and ligation. Our work reveals a remodeling event facilitating gRNA-mRNA hybridization and assembly of a macromolecular substrate for the editosome's catalytic modality.