5WSG

Cryo-EM structure of the Catalytic Step II spliceosome (C* complex) at 4.0 angstrom resolution

Summary for 5WSG

• Entry DOI: 10.2210/pdb5wsg/pdb
• EMDB information: 6684
• Descriptor: Pre-mRNA-splicing factor 8, Pre-mRNA-splicing factor CWC22, 5'-exon, ... (38 entities in total)
• Functional Keywords: catalytic step ii spliceosome, c* spliceosome, rna binding protein-rna complex, rna binding protein/rna
• Biological source: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast); More
• Total number of polymer chains: 45
• Total formula weight: 2090498.41

Authors

Yan, C.,Wan, R.,Bai, R.,Huang, G.,Shi, Y. (deposition date: 2016-12-07, release date: 2017-01-25, Last modification date: 2025-07-02)

Primary citation

Yan, C.,Wan, R.,Bai, R.,Huang, G.,Shi, Y.
Structure of a yeast step II catalytically activated spliceosome
Science, 355:149-155, 2017

PubMed Abstract: Each cycle of precursor messenger RNA (pre-mRNA) splicing comprises two sequential reactions, first freeing the 5' exon and generating an intron lariat-3' exon and then ligating the two exons and releasing the intron lariat. The second reaction is executed by the step II catalytically activated spliceosome (known as the C* complex). Here, we present the cryo-electron microscopy structure of a C* complex from Saccharomyces cerevisiae at an average resolution of 4.0 angstroms. Compared with the preceding spliceosomal complex (C complex), the lariat junction has been translocated by 15 to 20 angstroms to vacate space for the incoming 3'-exon sequences. The step I splicing factors Cwc25 and Yju2 have been dissociated from the active site. Two catalytic motifs from Prp8 (the 1585 loop and the β finger of the ribonuclease H-like domain), along with the step II splicing factors Prp17 and Prp18 and other surrounding proteins, are poised to assist the second transesterification. These structural features, together with those reported for other spliceosomal complexes, yield a near-complete mechanistic picture on the splicing cycle.

PubMed: 27980089
DOI: 10.1126/science.aak9979

Experimental method

ELECTRON MICROSCOPY (4 Å)