Structure of the yeast spliceosomal postcatalytic P complex.
basic_science · Level V
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- Record sourced from PubMed, PMID 29146870.
- Also identified by DOI 10.1126/science.aar3462 and PMC identifier 5828012.
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Abstract
The spliceosome undergoes dramatic changes in a splicing cycle. Structures of B, B<sup>act</sup>, C, C*, and intron lariat spliceosome complexes revealed mechanisms of 5'-splice site (ss) recognition, branching, and intron release, but lacked information on 3'-ss recognition, exon ligation, and exon release. Here we report a cryo-electron microscopy structure of the postcatalytic P complex at 3.3-angstrom resolution, revealing that the 3' ss is mainly recognized through non-Watson-Crick base pairing with the 5' ss and branch point. Furthermore, one or more unidentified proteins become stably associated with the P complex, securing the 3' exon and potentially regulating activity of the helicase Prp22. Prp22 binds nucleotides 15 to 21 in the 3' exon, enabling it to pull the intron-exon or ligated exons in a 3' to 5' direction to achieve 3'-ss proofreading or exon release, respectively.
Medical subject headings
- DEAD-box RNA Helicases
- Multienzyme Complexes
- RNA Splicing
- RNA Splicing Factors
- Ribonucleoprotein, U4-U6 Small Nuclear
- Ribonucleoprotein, U5 Small Nuclear
- Saccharomyces cerevisiae
- Saccharomyces cerevisiae Proteins
- Spliceosomes