Genetic Dissection of an RNA Enzyme

The group I introns are characterized by short conserved sequences and a highly conserved secondary structure. Several members of this class of introns have been shown to be capable of self-splicing in vitro, without the participation of any proteins. The best-characterized example of a self-splicing group I intron is the intron from the nuclear rRNA genes of Tetrahymena thermophila, originally shown to be self-splicing by Cech and his colleagues (Kruger et al. 1982; Zaug et al. 1983).