Maxizymes, novel allosterically controllable ribozymes, can be designed tocleave various substrates

We demonstrated previously that an allosterically controllable novel ribozy me, designated the maxizyme, is a powerful tool for disruption of an abnorm al chimeric RNA target [BCR-ABL (b2a2) mRNA], and we proposed that it might provide the basis for future gene therapy for the treatment of chronic mye logenous leukemia (Kuwabara et al. Mol. Cell 1998, 2, 617-627). The maxizym e has sensor arms that can recognize a specific sequence and, in the presen ce exclusively of such a specific sequence, it can form a cavity for captur e of catalytically indispensable Mg2+ ions. Cleavage of the target RNA then occurs at a site distant from the specific sequence. Clearly, the specific sequences recognized by sensor arms should not be limited to those of the above mentioned abnormal chimeric target. Thus, to demonstrate the general applicability of maxizyme technology, we constructed maxizymes targeted to other mRNAs, such as PML-RAR alpha mRNA, sDLST mRNA, and BCR-ABL (bla2) mRN A, that are not cleaved with high specificity by the wild-type hammerhead r ibozyme. Specific and efficient cleavage in vitro of these mRNAs by the cus tom-designed maxizymes demonstrated clearly that maxizyme technology is not limited to a specific case but may have broad general applicability in mol ecular biology and, also, in a clinical setting.