2026-07-21 中国科学院（CAS）
＜関連情報＞
- https://english.cas.cn/newsroom/research-news/202607/t20260716_1178503.shtml
- https://www.cell.com/cell/abstract/S0092-8674(26)00624-0
完全なイントロン除去によって生成されたスプライソソーム非依存性真核生物 A spliceosome-independent eukaryote generated by complete intron removal
Xin Man ∙ Wen-Ting Zhang ∙ Yu-Di Zhang ∙ … ∙ Pengfei Dai ∙ Weimin Jiang ∙ Jin-Qiu Zhou
Cell Published: July 15, 2026
DOI:https://doi.org/10.1016/j.cell.2026.05.033
Highlights
- Complete intron elimination renders the spliceosome nonessential
- U3 snoRNA splicing reveals distinct spliceosomal requirements
- Growth defects from intron loss are recessive and linked to ribosome biogenesis
- An intron-free eukaryote provides a minimal system to study genome evolution
Summary
Spliceosomal introns impose a universal processing burden on eukaryotes and obstruct genome minimization because their essentiality remains unresolved. By exploiting Spo11-independent meiosis in synthetic single-chromosome Saccharomyces cerevisiae, the complete deletion of all 300 spliceosomal introns was achieved, generating an intron-free strain, SYNE27α. Whole-genome sequencing confirmed precise excision. Unexpectedly, spliceosomal components (all five small nuclear RNAs [snRNAs], Prp8, Prp9, Prp19, Yhc1, and Luc7) were no longer required for viability, demonstrating that a eukaryotic cell can exist independently of spliceosomal function. U3 small nucleolar RNA (snoRNA) splicing bypassed the requirements for Yhc1, Luc7, Prp9, and Prp19, revealing a mechanistic divergence from pre-mRNA splicing. Cumulative intron loss caused slow growth via ribosomal dysregulation, yet SYNE27α maintained genetic stability. Fitness costs were fully recessive in diploids, confirming intron loss as the primary driver. These findings establish an intron-free, spliceosome-independent eukaryote, resolving the essential function of the spliceosome and enabling minimal-system studies of genome evolution.
