Structures Involved in Tetrahymena rRNA Self-splicing and RNA Enzyme Activity
This extract was created in the absence of an abstract.
Excerpt
In eukaryotic genes, coding sequences in the DNA are often interrupted by stretches of noncoding DNA. These intervening sequences (IVSs), or introns, are transcribed along with the flanking coding sequences (exons) to give a large precursor RNA. RNA splicing is the process by which the IVSs are removed from the precursor and the exons are ligated.
Three major classes of RNA splicing can be delineated on the basis of splicing mechanism. Nuclear tRNA precursors undergo splicing by separable cleavage and rejoining reactions, which are catalyzed by traditional enzymes, including endonucleases and ligases (Filipowicz and Shatkin 1983; Greer et al. 1983). Group I RNA precursors include examples from fungal mitochondrial pre-mRNAs and pre-rRNAs, the nuclear pre-rRNA of Tetrahymena and Physarum, and several bacteriophage pre-mRNAs (Michel and Dujon 1983; Waring et al. 1983; Chu et al. 1986). They undergo splicing by a two-step transesterification mechanism (Fig. 1) and exemplify intramolecular catalysis; i.e.,...
