Abstract
Self-splicing of the group I IVS from Tetrahymena thermophila rDNA is limited by the time required for the RNA to reach its active conformation. In vitro, folding is slow because the pre-rNA becomes kinetically trapped in inactive structures. In vivo, splicing is 50 times more rapid, implying that misfolding of the pre-rRNA is corrected. Exon mutations that inhibit self-splicing 100-fold in vitro were fully rescued when the pre-rRNA containing the IVS was expressed in E. coli. In contrast, IVS mutations that cause misfolding were only partially suppressed at 42°C, and doubled the activation energy of splicing. These results suggest that intracellular folding of the pre-rRNA involves metastable intermediates similar to those observed in vitro. Precursors with natural rRNA exons were more active and less cold-sensitive than those with non-rRNA exons. This shows that the rRNA reduces misfolding of the IVS, thereby facilitating splicing of the pre-rRNA in vitro.
Original language | English (US) |
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Pages (from-to) | 557-567 |
Number of pages | 11 |
Journal | Journal of molecular biology |
Volume | 292 |
Issue number | 3 |
DOIs | |
State | Published - Sep 24 1999 |
Keywords
- Group I intron
- RNA folding
- Ribosomal RNA
- Self-splicing
ASJC Scopus subject areas
- Structural Biology
- Molecular Biology