Summary information and primary citation
- PDB-id
-
6j6q;
DSSR-derived features in text and
JSON formats
- Class
- splicing
- Method
- cryo-EM (3.7 Å)
- Summary
- cryo-EM structure of the yeast b*-b2 complex at an
average resolution of 3.7 angstrom
- Reference
-
Wan R, Bai R, Yan C, Lei J, Shi Y (2019): "Structures
of the Catalytically Activated Yeast Spliceosome Reveal
the Mechanism of Branching." Cell,
177, 339-351.e13. doi: 10.1016/j.cell.2019.02.006.
- Abstract
- Pre-mRNA splicing is executed by the spliceosome.
Structural characterization of the catalytically activated
complex (B<sub>∗</sub>) is pivotal for
understanding the branching reaction. In this study,
we assembled the B<sub>∗</sub> complexes
on two different pre-mRNAs from Saccharomyces cerevisiae
and determined the cryo-EM structures of four distinct
B<sub>∗</sub> 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<sub>∗</sub> 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.
