6G90

Prespliceosome structure provides insight into spliceosome assembly and regulation (map A2)

Summary for 6G90

• Entry DOI: 10.2210/pdb6g90/pdb
• EMDB information: 4364
• Descriptor: U1 snRNA,U1 snRNA,U1 snRNA,U1 snRNA,U1 snRNA, Protein LUC7,Protein LUC7,Protein LUC7, Yeast UBC4 pre-mRNA (mutant), ... (32 entities in total)
• Functional Keywords: spliceosome, a complex, rna processing, rna-protein complex, splicing
• Biological source: Saccharomyces cerevisiae; More
• Total number of polymer chains: 38
• Total formula weight: 1346391.44

Authors

Plaschka, C.,Lin, P.-C.,Charenton, C.,Nagai, K. (deposition date: 2018-04-10, release date: 2018-08-22, Last modification date: 2024-10-23)

Primary citation

Plaschka, C.,Lin, P.C.,Charenton, C.,Nagai, K.
Prespliceosome structure provides insights into spliceosome assembly and regulation.
Nature, 559:419-422, 2018

PubMed Abstract: The spliceosome catalyses the excision of introns from pre-mRNA in two steps, branching and exon ligation, and is assembled from five small nuclear ribonucleoprotein particles (snRNPs; U1, U2, U4, U5, U6) and numerous non-snRNP factors. For branching, the intron 5' splice site and the branch point sequence are selected and brought by the U1 and U2 snRNPs into the prespliceosome, which is a focal point for regulation by alternative splicing factors. The U4/U6.U5 tri-snRNP subsequently joins the prespliceosome to form the complete pre-catalytic spliceosome. Recent studies have revealed the structural basis of the branching and exon-ligation reactions, however, the structural basis of the early events in spliceosome assembly remains poorly understood. Here we report the cryo-electron microscopy structure of the yeast Saccharomyces cerevisiae prespliceosome at near-atomic resolution. The structure reveals an induced stabilization of the 5' splice site in the U1 snRNP, and provides structural insights into the functions of the human alternative splicing factors LUC7-like (yeast Luc7) and TIA-1 (yeast Nam8), both of which have been linked to human disease. In the prespliceosome, the U1 snRNP associates with the U2 snRNP through a stable contact with the U2 3' domain and a transient yeast-specific contact with the U2 SF3b-containing 5' region, leaving its tri-snRNP-binding interface fully exposed. The results suggest mechanisms for 5' splice site transfer to the U6 ACAGAGA region within the assembled spliceosome and for its subsequent conversion to the activation-competent B-complex spliceosome. Taken together, the data provide a working model to investigate the early steps of spliceosome assembly.

PubMed: 29995849
DOI: 10.1038/s41586-018-0323-8

Experimental method

ELECTRON MICROSCOPY (4 Å)