A newt ribozyme: a catalytic activity in search of a function.

We analyzed the cleavage properties and the transcription regulation of the newt (Triturus vulgaris meridionalis) self-cleaving RNA. In vitro self-cleavage of model oligoribonucleotides occurs within a double hammerhead structure. In addition, an entire ribozyme molecule, as well as its catalytic domain, "trans-cleaves" in vitro appropriate oligoribonucleotide substrates. Signals encoded within the ribozyme DNA sequences regulate the ribozyme transcription, which is RNA polymerase II dependent. Finally, the deduced secondary structure of the self-cleaving RNA appears to be conserved in evolutionarily distant newt species. These features suggest that the newt ribozyme could play some role in the cell, possibly related to its cleavage properties.