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Title | Structures of the Catalytically Activated Yeast Spliceosome Reveal the Mechanism of Branching. |
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Journal, issue, pages | Cell, Vol. 177, Issue 2, Page 339-351.e13, Year 2019 |
Publish date | Apr 4, 2019 |
Authors | Ruixue Wan / Rui Bai / Chuangye Yan / Jianlin Lei / Yigong Shi / |
PubMed Abstract | Pre-mRNA splicing is executed by the spliceosome. Structural characterization of the catalytically activated complex (B) is pivotal for understanding the branching reaction. In this study, we ...Pre-mRNA splicing is executed by the spliceosome. Structural characterization of the catalytically activated complex (B) is pivotal for understanding the branching reaction. In this study, we assembled the B complexes on two different pre-mRNAs from Saccharomyces cerevisiae and determined the cryo-EM structures of four distinct B complexes at overall resolutions of 2.9-3.8 Å. The duplex between U2 small nuclear RNA (snRNA) and the branch point sequence (BPS) is discretely away from the 5'-splice site (5'SS) in the three B complexes that are devoid of the step I splicing factors Yju2 and Cwc25. Recruitment of Yju2 into the active site brings the U2/BPS duplex into the vicinity of 5'SS, with the BPS nucleophile positioned 4 Å away from the catalytic metal M2. This analysis reveals the functional mechanism of Yju2 and Cwc25 in branching. These structures on different pre-mRNAs reveal substrate-specific conformations of the spliceosome in a major functional state. |
External links | Cell / PubMed:30879786 |
Methods | EM (single particle) |
Resolution | 2.9 - 3.86 Å |
Structure data | EMDB-0684: EMDB-0685: EMDB-0686, PDB-6j6g: EMDB-0687, PDB-6j6h: |
Chemicals | ChemComp-IHP: ChemComp-GTP: ChemComp-MG: ChemComp-ZN: |
Source |
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Keywords | SPLICING / spliceosme / B* complex / branching / snRNP / U snRNA / spliceosome |