Cleavage of the highly conserved hairpin-loop region of HIV-1 by synthetic ribozymes.

Hammerhead ribozymes can be considered as molecular scissors for suppressing AIDS virus. It is attractive to target single-stranded region of HIV-1 RNA because single-stranded RNA interactions or "kissing" induce hybridization. We, therefore, chose a highly conserved hairpin-loop structure, that is located in the 5' long terminal repeat region and just downstream of the TAR regulatory sequence. As a model system, we synthesized the corresponding hairpin-loop structure (21-mer RNA) and several types of ribozyme that are different in sizes in the hybridizing arms. These ribozymes successfully cleaved the 21-mer hairpin-structured substrate after CUU sequence but with different efficiencies.