Four-stranded DNA structure stabilized by a novel G:C:A:T tetrad.
The solution structure of a cyclic oligonucleotide d<pCGCTCATT> 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.
Departament de Química Orgànica, Universitat de Barcelona, C/, Martí i Franquès 1-11, 08028 Barcelona, Spain.
Núria
N
Escaja
Josep Lluis
JL
Gelpí
Modesto
M
Orozco
Manuel
M
Rico
Enrique
E
Pedroso
Carlos
C
González
D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D054856:G-Quadruplexes; D007700:Kinetics; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D012996:Solutions; D013816:Thermodynamics
D009841:Oligonucleotides; D012996:Solutions; D004247:DNA