Masaki Warashina

A novel allosterically trans-activated ribozyme, the maxizyme, with exceptional specificity in vitro and in vivo.

We have constructed an allosterically controllable novel enzyme (designated maxizyme) that can be transcribed in vivo under the control of a human tRNA(Val) promoter. The maxizyme has sensor arms that can recognize target sequences, and in the presence of such a target sequence only, it can form a cavity that can capture catalytically indispensable Mg2+ ions. As a target for a demonstration of the potential utility of the maxizyme, we chose BCR-ABL mRNA, the translated products of which cause chronic myelogenous leukemia. Only the maxizyme (but not conventional ribozymes) had extremely high specificity and high-level activity, not only in vitro but also in cultured cells including BV173 cells derived from a patient with a Philadelphia chromosome. The maxizyme induced apoptosis only in leukemic cells with this chromosome.

Allosterically controllable maxizymes cleave mRNA with high efficiency and specificity

Ribozymes are small and versatile nucleic acids that can cleave RNA molecules at specific sites. However, because of the limited number of cleavable sequences on the target mRNA, in some cases conventional ribozymes do not have precise cleavage specificity. To overcome this problem, an allosteric version (a maxizyme) was developed that displayed activity and specificity in vivo. More than five custom-designed maxizymes have demonstrated sensor functions, which indicates that the technology might be broadly applicable in molecular biology and possibly in the clinic.