6j6q
Cryo-EM structure of the yeast B*-b2 complex at an average resolution of 3.7 angstrom
Structural highlights
FunctionPRP8_YEAST Required for pre-spliceosome formation, which is the first step of pre-mRNA splicing. This protein is associated with snRNP U5. Has a role in branch site-3' splice site selection. Associates with the branch site-3' splice 3'-exon region. Also has a role in cell cycle.[1] [2] [3] [4] Publication Abstract from PubMedPre-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 A. 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 A 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. Structures of the Catalytically Activated Yeast Spliceosome Reveal the Mechanism of Branching.,Wan R, Bai R, Yan C, Lei J, Shi Y Cell. 2019 Apr 4;177(2):339-351.e13. doi: 10.1016/j.cell.2019.02.006. Epub 2019, Mar 14. PMID:30879786[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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