Figure 2.

Rz- or substrate-encoding plasmids were linearized at their 3′ ends as described in Materials and Methods and subjected to in vitro transcription using a kit from Promega. The synthesis of synthetic s1 RNA, which is 174 nts long, is shown in lane 1. When equimolar amounts (0.3 pmols) of unlabeled Rz and labeled substrate RNA are mixed in the presence of 10 mM MgCl₂, specific cleavage products (112 and 62 nts long) could be seen (lane 2). Under exactly similar experimental conditions the mutant S1–553-Rz failed to cleave the target RNA (lane 3). Specific cleavage products also were observed with Rz-984 (see Fig. 3B).