Efficient trans cleavage and a common structural motif for the ribozymes of the human hepatitis delta agent

Cis-active ribozymes are potential therapeutic agents; however, to be used in this capacity, they must first be converted to trans-active ribozymes, a process facilitated by analysis of their structures. We present evidence that the genomic and antigenomic ribozymes of the human delta hepatitis agent share a structural ("axehead") motif that has conserved sequence elements and a stable hairpin. Guided by the features of the axehead, we divided each of the delta ribozymes into two subdomains, which we synthesized as separate RNA transcripts to give an enzyme and substrate for each ribozyme. Incubation of a substrate subdomain with its matching enzyme resulted in efficient and accurate trans cleavage. This work forms the basis for kinetic studies and for adapting the delta ribozymes for cleavage of selected target RNAs.