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

• 成果类型: Article
• 署名作者: 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
• 署名单位: University of California System; University of California Los Angeles; University of California System; University of California Los Angeles; Boston University; ShanghaiTech University; University of California System; University of California Irvine; Boston University
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-13126
• DOI: 10.1126/science.adg4725
• 发表日期: 2023-07-07
• 页码: 43-+
• 关键词: guide rna; binding complex; kinetoplastid mitochondria; protein; brucei; transcripts; specificity; domain; endonuclease; purification

摘要

In Trypanosoma brucei, 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.