Research Article

Structures of the fully assembled Saccharomyces cerevisiae spliceosome before activation

See allHide authors and affiliations

Science  24 May 2018:
eaau0325
DOI: 10.1126/science.aau0325

You are currently viewing the abstract.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

Abstract

The pre-catalytic spliceosome (B complex) is preceded by the pre-B complex. Here we report the cryo-EM structures of the Saccharomyces cerevisiae pre-B and B complexes at average resolutions of 3.3-4.6 and 3.9 Å, respectively. In the pre-B complex, the duplex between the 5′-splice site (5′SS) and U1 snRNA is recognized by Yhc1, Luc7, and the Sm ring. In the B complex, U1 snRNP is dissociated, the 5′-exon-5′SS sequences are translocated near U6 snRNA, and three B-specific proteins may orient the pre-mRNA. In both complexes, U6 snRNA is anchored to loop I of U5 snRNA and the duplex between the branch point sequence and U2 snRNA is recognized by the SF3b complex. Structural analysis reveals the mechanism of assembly and activation for the yeast spliceosome.

View Full Text