Interrogation of highly structured RNA with multicomponent deoxyribozyme probes at ambient temperatures

Abstract

Molecular analysis of RNA through hybridization with sequence-specific probes is challenging due to the intrinsic ability of RNA molecules to form stable secondary and tertiary structures. To overcome the energy barrier toward the probe–RNA complex formation, the probes are made of artificial nucleotides, which are more expensive than their natural counterparts and may still be inefficient. Here, we propose the use of a multicomponent probe based on an RNA-cleaving deoxyribozyme for the analysis of highly structured RNA targets. Efficient interrogation of two native RNA from Saccharomyces cerevisiae—a transfer RNA (tRNA) and 18S ribosomal RNA (rRNA)—was achieved at ambient temperature. We achieved detection limits of tRNA down to ∼0.3 nM, which is two orders of magnitude lower than that previously reported for molecular beacon probes. Importantly, no probe annealing to the target was required, with the hybridization assay performed at 37°C. Excess of nonspecific targets did not compromise the performance of the probe, and high interrogation efficiency was maintained by the probes even in complex matrices, such as cell lysate. A linear dynamic range of 0.3–150 nM tRNA was demonstrated. The probe can be adapted for differentiation of a single mismatch in the tRNA–probe complex. Therefore, this study opens a venue toward highly selective, sensitive, robust, and inexpensive assays for the interrogation of biological RNA.