Facilitation of group I splicing in vivo: Misfolding of the Tetrahymena IVS and the role of ribosomal RNA exons

Tania Nikolcheva, Sarah A. Woodson

Research output: Contribution to journalArticle

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 languageEnglish (US)
Pages (from-to)557-567
Number of pages11
JournalJournal of molecular biology
Volume292
Issue number3
DOIs
StatePublished - Sep 24 1999

Keywords

  • Group I intron
  • RNA folding
  • Ribosomal RNA
  • Self-splicing

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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