Structural and sequence elements required for the self-cleaving activity of the hepatitis delta virus ribozyme

The hepatitis delta virus (HDV) is a subviral RNA that contains a self-cleaving activity that is similar to the ribozyme activity found in certain plant pathogens. However, the sequences surrounding the cleavage site are unrelated to the hammerhead or hairpin ribozyme motifs, and it is considered to be a distinct ribozyme type. We made site-specific changes within two regions of the smallest contiguous HDV sequence that has optimal activity and kinetically analyzed the data at different temperatures to determine the potential roles of the residues. We distinguish between those changes that affect the rate of catalysis and those that promote the formation of inactive structures