Efficient Trans Cleavage and a Common Structural Motif for the Ribozymes of the Human Hepatitis δ 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 Δ 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 Δ 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 Δ ribozymes for cleavage of selected target RNAs.