FIGURE 1.

Structure and proposed kinetic pathway of the HDV ribozyme. (A) Secondary structure and nucleotide sequence of the HDV ribozyme derived from the antigenomic hepatitis delta virus genome. The numbering system is that of Shih and Been (2002). The Δ in the L4 loop indicates the P4 deletion compared to the natural variants. The wobble base pair at the bottom of the P1 stem is indicated by a single large dot, while the homopurine base pair at the top of the P4 stem is represented by two large dots. The base pairs of the P1.1 pseudoknot are indicated by the dotted lines. The arrow indicates the cleavage site. (B) Proposed kinetic pathway of the HDV ribozyme. S, Rz, PI, and PII represent the substrate, the ribozyme, and the 5′ and 3′ products, respectively.