Funding Organization(s): National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS), National Institutes of Health/National Institute Of Allergy and Infectious Diseases (NIH/NIAID)
The spliceosome undergoes dramatic changes in a splicing cycle. Structures of B, B act , 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 ...
The spliceosome undergoes dramatic changes in a splicing cycle. Structures of B, B act , 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.
Organizational Affiliation:
Department of Biochemistry and Molecular Genetics, University of Colorado Denver (UCD), Anschutz Medical Campus, Aurora, CO 80045, USA. rui.zhao@ucdenver.edu hong.zhou@ucla.edu.
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