Intron lariat spliceosomes convert lariats to true circles: implications for intron transposition
- 1Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, California 95064, USA;
- 2Genomics Institute, University of California, Santa Cruz, Santa Cruz, California 95064, USA
- Corresponding author: ares{at}ucsc.edu
Abstract
Rare, full-length circular intron RNAs distinct from lariats have been reported in several species, but their biogenesis is not understood. We envisioned and tested a hypothesis for their formation using Saccharomyces cerevisiae, documenting full-length and novel processed circular RNAs from multiple introns. Evidence implicates a previously undescribed catalytic activity of the intron lariat spliceosome (ILS) in which the 3′-OH of the lariat tail (with optional trimming and adenylation by the nuclear 3′ processing machinery) attacks the branch, joining the intron 3′ end to the 5′ splice site in a 3′–5′ linked circle. Human U2 and U12 spliceosomes produce analogous full-length and processed circles. Postsplicing catalytic activity of the spliceosome may promote intron transposition during eukaryotic genome evolution.
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Footnotes
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Supplemental material is available for this article.
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Article published online ahead of print. Article and publication date are online at http://www.genesdev.org/cgi/doi/10.1101/gad.351764.124.
- Received March 30, 2024.
- Accepted April 24, 2024.
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