Four-stranded DNA structure stabilized by a novel G:C:A:T tetrad.

TitleFour-stranded DNA structure stabilized by a novel G:C:A:T tetrad.
Publication TypeJournal Article
Year of Publication2003
AuthorsEscaja, Núria, Gelpí Josep-Lluis, Orozco Modesto, Rico Manuel, Pedroso Enrique, and González Carlos
JournalJ Am Chem Soc
Date Published2003 May 14
KeywordsBase Pairing, Biomolecular, DNA, G-Quadruplexes, Kinetics, Models, Molecular, Nuclear Magnetic Resonance, Nucleic Acid Conformation, Oligonucleotides, Solutions, Thermodynamics

The solution structure of a cyclic oligonucleotide d
has been determined by two-dimensional NMR spectroscopy and restrained molecular dynamics. Under the appropriate experimental conditions, this molecule self-associates, forming a symmetric dimer stabilized by four intermolecular Watson-Crick base pairs. The resulting four-stranded structure consists of two G:C:A:T tetrads, formed by facing the minor groove side of the Watson-Crick base-pairs. Most probably, the association of the base-pairs is stabilized by coordinating a Na(+) cation. This is the first time that this novel G:C:A:T tetrad has been found in an oligonucleotide structure. This observation increases considerably the number of sequences that may adopt a four-stranded architecture. Overall, the three-dimensional structure is similar to those observed previously in other quadruplexes formed by minor groove alignment of Watson-Crick base pairs. This resemblance strongly suggests that we may be observing a general motif for DNA-DNA recognition.