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Local conformational changes in the 8–17 deoxyribozyme core induced by activating and inactivating divalent metal ions

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Abstract

The 8–17 deoxyribozyme (DNAzyme) is a catalytic DNA molecule capable of cleaving specific RNA substrates. The deoxyribozyme is activated by a wide variety of divalent metal ions, from Mg2+ to Pb2+, with just a few exceptions. It is not clear if metal ions are directly involved in catalysis, or are required to attain an active conformation, or both. In particular, the connection between metal-induced global structural rearrangements and catalysis is not straightforward. To gain more information on the local structural changes induced by metal ions, we introduced fluorescent 2-aminopurine (2-Ap) residues at different positions of the 8–17 ‘core’. We found that a construct containing 2-Ap at position 15 was best suited to monitor conformational changes in the presence of Mg2+, Ca2+ or Mn2+. Binding of these activating metal ions caused a local rearrangement at position 15, apparently entailing decreased stacking of the 2-Ap base. The metal dependence for such conformational change was generally hyperbolic (suggesting it mirrored the binding by a single metal ion) and yielded apparent dissociation constants close to those required for activation. In contrast, Cu2+, a divalent metal ion which does not support catalysis, caused in the deoxyribozyme a slow, reversible inactivation, which correlated with a very distinct conformational change at position 15.

Graphical abstract: Local conformational changes in the 8–17 deoxyribozyme core induced by activating and inactivating divalent metal ions

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Publication details

The article was received on 11 Aug 2017, accepted on 04 Oct 2017 and first published on 04 Oct 2017


Article type: Paper
DOI: 10.1039/C7OB02001E
Citation: Org. Biomol. Chem., 2017, Advance Article
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    Local conformational changes in the 8–17 deoxyribozyme core induced by activating and inactivating divalent metal ions

    A. Peracchi, M. Bonaccio and A. Credali, Org. Biomol. Chem., 2017, Advance Article , DOI: 10.1039/C7OB02001E

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