6J6Q

Cryo-EM structure of the yeast B*-b2 complex at an average resolution of 3.7 angstrom

Summary for 6J6Q

• Entry DOI: 10.2210/pdb6j6q/pdb
• EMDB information: 0692
• Descriptor: Pre-mRNA-splicing factor 8, Pre-mRNA-splicing factor CWC22, Pre-mRNA-splicing factor CEF1, ... (36 entities in total)
• Functional Keywords: spliceosme, b* complex, branching, snrnp, u snrna, splicing
• Biological source: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast); More
• Total number of polymer chains: 42
• Total formula weight: 2108228.78

Authors

Wan, R.,Bai, R.,Yan, C.,Lei, J.,Shi, Y. (deposition date: 2019-01-15, release date: 2019-04-24, Last modification date: 2020-10-14)

Primary citation

Wan, R.,Bai, R.,Yan, C.,Lei, J.,Shi, Y.
Structures of the Catalytically Activated Yeast Spliceosome Reveal the Mechanism of Branching.
Cell, 177:339-351.e13, 2019

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 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.

PubMed: 30879786
DOI: 10.1016/j.cell.2019.02.006

Experimental method

ELECTRON MICROSCOPY (3.7 Å)