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Refolding of rRNA exons enhances dissociation of the Tetrahymena intron

Published online by Cambridge University Press:  01 September 2000

YONG CAO  and
SARAH A. WOODSON
YONG CAO
Affiliation:
Molecular and Cell Biology Program, University of Maryland, College Park, Maryland 20742-2021, USA Present address: Department of Microbiology and Immunology, Virginia Commonwealth University Medical College, P.O. Box 980678, Richmond, Virginia 23298-0678, USA.
SARAH A. WOODSON
Affiliation:
Molecular and Cell Biology Program, University of Maryland, College Park, Maryland 20742-2021, USA Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-2021, USA Present address: T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, USA.
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Abstract

Self-splicing of the Tetrahymena pre-rRNA is inhibited by a conserved rRNA hairpin P(−1) upstream of the 5′ splice site. P(−1) inhibits self-splicing by competing with formation of the P1 splice site helix. Here we show that the P(−1) hairpin also enhances dissociation of the spliced products, which was monitored by native gel electrophoresis. Mutations that stabilize the rRNA hairpin increase the rate of dissociation approximately 10-fold, from 0.5 min−1 for the wild-type RNA to ∼4 min−1 at 30 °C. Conversely, mutations or oligonucleotides that inhibit refolding of the exons and that stabilize the P1 helix decrease the rate of product release. The results suggest that refolding of products can be used to stimulate the turnover of ribozyme-catalyzed reactions. In the pre-rRNA, this conformational change helps shift the equilibrium of self-splicing toward the mature rRNA.

Keywords

group I intronproduct dissociationribozymerRNAself-splicing
Type
Research Article
Information
RNA , Volume 6 , Issue 9 , September 2000 , pp. 1248 - 1256
Copyright
2000 RNA Society

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