Proc Natl Acad Sci U S A 80: 3903-7 (1983)
Abstract
Splicing of the ribosomal RNA precursor of Tetrahymena is an
autocatalytic reaction, requiring no enzyme or other protein in vitro.
The structure of the intervening sequence (IVS) appears to direct the
cleavage/ligation reactions involved in pre-rRNA splicing and IVS
cyclization. We have probed this structure by treating the linear
excised IVS RNA under nondenaturing conditions with various single- and
double-strand-specific nucleases and then mapping the cleavage sites by
using sequencing gel electrophoresis. A computer program was then used
to predict the lowest-free-energy secondary structure consistent with
the nuclease cleavage data. The resulting structure is appealing in that
the ends of the IVS are in proximity; thus, the IVS can help align the
adjacent coding regions (exons) for ligation, and IVS cyclization can
occur. The Tetrahymena IVS has several sequences in common with those of
fungal mitochondrial mRNA and rRNA IVSs, sequences that by genetic
analysis are known to be important cis-acting elements for splicing of
the mitochondrial RNAs. In the predicted structure of the Tetrahymena
IVS, these sequences interact in a pairwise manner similar to that
postulated for the mitochondrial IVSs. These findings suggest a common
origin of some nuclear and mitochondrial introns and common elements in
the mechanism of their splicing.
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Chemical Identifiers (Names)