An RNA-Cleaving DNAzyme That Requires an Organic Solvent to Function.

Abstract

Engineering functional nucleic acids active under unusual conditions will not only reveal the hidden talents of nucleic acids but also lay groundwork for pursuing them for unique applications. Although many DNAzymes have been derived to catalyze diverse chemical reactions in aqueous solutions, no prior study has been set up to purposely derive DNAzymes that require an organic solvent to function. Herein, we utilized in vitro selection to isolate RNA-cleaving DNAzymes from a random-sequence DNA pool that were "compelled" to accept 35% dimethyl sulfoxide (DMSO) as a cosolvent, via counter selection in a purely aqueous solution followed by positive selection in the same solution containing 35% DMSO. This experiment indeed led to the discovery of a new DNAzyme that requires 35% DMSO for its catalytic activity but exhibits drastically reduced activity without DMSO. This DNAzyme also requires divalent metal ions for catalysis and uses monovalent ions for activity enhancement. A minimized, more efficient DNAzyme was also derived. This work demonstrates that highly functional organic solvent-dependent DNAzymes can be isolated from random-sequence DNA libraries via forced in vitro selection, thus expanding the capability and potential utility of DNA as enzymes.