FIG. 2.

Construction of plasmids pHSP1 and pHSR1 and nucleotide sequence and secondary-structure model of the RNA expressed. (a) Organization of RNA aptamer (streptavidin RNA aptamer) expression sites designed in the plasmids. The plasmids pHSP1 and pHSR1 contained the puf promoter and the rrn promoter, respectively. (b) Predicted secondary structure of the expressed RNA. The streptavidin RNA aptamer with flanking hammerhead ribozyme sequences is shown. The self-cleavage sites expected in hammerhead ribozyme reactions are indicated by small arrows. 101N and 126N indicate the predicted additional lengths expressed from the plasmid pHSR1 (rrn promoter). The EcoRI and HindIII sites used for cloning (see Materials and Methods) are indicated.