Enzymatic activity of the conserved core of a group I self-splicing intron

Splicing of the Tetrahymena ribosomal intron was first studied by Cech et al., who subsequently demonstrated that the intron RNA catalyses its own excision from a primary transcript to yield mature ribosomal RNA. This intron shares several short conserved sequences and a common secondary structure with several other introns, some of which have also been shown to self-splice. Here I show that the conserved core of the Tetrahymena intron can act in trans to catalyse the sequence-specific cleavage and addition of guanosine to a separate RNA substrate.