Time-resolved structural analysis of an RNA-cleaving DNA catalyst.

The 10-23 DNAzyme is one of the most prominent catalytically active DNA sequences 1,2 . Its ability to cleave a wide range of RNA targets with high selectivity entails a substantial therapeutic and biotechnological potential 2 . However, the high expectations have not yet been met, a fact that coincides with the lack of high-resolution and time-resolved information about its mode of action 3 . Here we provide high-resolution NMR characterization of all apparent states of the prototypic 10-23 DNAzyme and present a comprehensive survey of the kinetics and dynamics of its catalytic function. The determined structure and identified metal-ion-binding sites of the precatalytic DNAzyme-RNA complex reveal that the basis of the DNA-mediated catalysis is an interplay among three factors: an unexpected, yet exciting molecular architecture; distinct conformational plasticity; and dynamic modulation by metal ions. We further identify previously hidden rate-limiting transient intermediate states in the DNA-mediated catalytic process via real-time NMR measurements. Using a rationally selected single-atom replacement, we could considerably enhance the performance of the DNAzyme, demonstrating that the acquired knowledge of the molecular structure, its plasticity and the occurrence of long-lived intermediate states constitutes a valuable starting point for the rational design of next-generation DNAzymes.