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Título

Strand displacement of double-stranded DNA by triplex-forming antiparallel purine-hairpins

AutorComa, Sílvia; Eritja Casadellà, Ramón; Noé, Véronique; Ciudad, Carlos J.
Palabras clavedouble stranded DNA
DNA
nucleic acid
guanine
purine
pyrimidine derivative
Base Sequence
Electrophoretic Mobility Shift Assay
Nucleic acid conformation
Polymerase Chain Reaction
Fecha de publicación2005
EditorMary Ann Liebert
CitaciónOligonucleotides
ResumenWe characterize the binding affinity and the thermodynamics of hybridization of triplex-forming antiparallel purine-hairpins composed of two antiparallel purine domains linked by a loop directed toward single-stranded and double-stranded DNA (ssDNA, dsDNA). Gel retardation assays and melting experiments reveal that a 13-mer purine-hairpin binds specifically and with a Kd of 8 × 10-8 M to polypyrimidine ssDNA to form a triple helical structure. Remarkably, we show that purine-hairpins also bind polypurine/polypyrimidine stretches included in a dsDNA of several hundred bp in length. Binding of purine-hairpins to dsDNA occurs by triplex formation with the polypyrimidine strand, causing displacement of the polypurine strand. Because triplex formation is restricted to polypurine/polypyrimidine stretches of dsDNA, we studied the triplex formation between purine-hairpins and polypyrimidine targets containing purine interruptions. We found that an 11-mer purine-hairpin with an adenine opposite to a guanine interruption in the polypyrimidine track binds to ssDNA and dsDNA, allowing expansion of the possible target sites and increase in the length of purine-hairpins. Thus, when using a 20-mer purine-hairpin targeting an interruption-containing polypyrimidine target, the binding affinity is increased compared to its 13-mer antiparallel purine-hairpin counterpart. Surprisingly, this increase is much more pronounced than that observed for a tail-clamp purine-hairpin extended up to 20 nt in the Watson-Crick domain only. Thus, triplex-forming antiparallel purine-hairpins can be a potentially useful strategy for both single-strand and double-strand nucleic acid recognition.
Versión del editorDOI: 10.1089/oli.2005.15.269
URIhttp://hdl.handle.net/10261/124878
DOI10.1089/oli.2005.15.269
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