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Comamonas testosteroni KF-1 circularly permuted group II intron 2S stateComamonas testosteroni KF-1 circularly permuted group II intron 2S state
Structural highlights
Publication Abstract from PubMedCircularly permuted group II introns (CP introns) consist of rearranged structural domains separated by two tethered exons, generating branched introns and circular exons via back-splicing. Structural and mechanistic understanding of circular RNA (circRNA) generation by CP introns remains elusive. We resolve cryo-electron microscopy structures of a natural CP intron in different states during back-splicing at a resolution of 2.5-2.9 A. Domain 6 (D6) undergoes a conformational change of 65 degrees after branching, to facilitate 3'-exon recognition and circularization. Previously unseen tertiary interactions compact the catalytic triad and D6 for splicing without protein, whereas a metal ion, M(35), is observed to stabilize the 5'-exon during splicing. While these unique features were not observed in canonical group II introns and spliceosomes, they are common in CP introns, as demonstrated by the cryo-EM structure of another CP intron discovered by comparative genomics analysis. Our results elucidate the mechanism of CP intron back-splicing dynamics, with potential applications in circRNA research and therapeutics. Structural basis of circularly permuted group II intron self-splicing.,Wang L, Xie J, Zhang C, Zou J, Huang Z, Shang S, Chen X, Yang Y, Liu J, Dong H, Huang D, Su Z Nat Struct Mol Biol. 2025 Jan 31. doi: 10.1038/s41594-025-01484-x. PMID:39890981[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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