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Solution structure of a DNA double helix with consecutive metal-mediated base pairs

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Johannsen S, Megger N, Bohme D, Sigel RKO, Muller J,
Project Coordination Chemistry within the Core of Large RNAs: Regulating Tertiary Contacts and Function
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Original article (peer-reviewed)

Journal NATURE CHEMISTRY
Volume (Issue) 2(3)
Page(s) 229 - 234
Title of proceedings NATURE CHEMISTRY

Abstract

Metal-mediated base pairs represent a powerful tool for the site-specific functionalization of nucleic acids with metal ions. The development of applications of the metal-modified nucleic acids will depend on the availability of structural information on these double helices. We present here the NMR solution structure of a self-complementary DNA oligonucleotide with three consecutive imidazole nucleotides in its centre. In the absence of transition-metal ions, a hairpin structure is adopted with the artificial nucleotides forming the loop. In the presence of Ag(I) ions, a duplex comprising three imidazole–Ag+–imidazole base pairs is formed. Direct proof for the formation of metal-mediated base pairs was obtained from 1J(15N,107/109Ag) couplings upon incorporation of 15N-labelled imidazole. The duplex adopts a B-type conformation with only minor deviations in the region of the artificial bases. This work represents the first structural characterization of a metalmodified nucleic acid with a continuous stretch of metal-mediated base pairs.
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