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Title: Polypurine reverse-Hoogsteen (PPRH) oligonucleotides can form triplexes with their target sequences even under conditions where they fold into G-quadruplexes
Author: Solé, Anna
Delagoutte, Emmanuelle
Ciudad i Gómez, Carlos Julián
Noé Mata, Verónica
Alberti, Patrizia
Keywords: ADN
Estructura molecular
Molecular structure
Issue Date: 9-Jan-2017
Publisher: Nature Publishing Group
Abstract: Polypurine reverse-Hoogsteen (PPRH) oligonucleotides are non-modified DNA molecules composed of two mirror-symmetrical polypurine stretches linked by a five-thymidine loop. They can fold into reverse-Hoogsteen hairpins and bind to their polypyrimidine target sequence by Watson-Crick bonds forming a three-stranded structure. They have been successfully used to knockdown gene expression and to repair single-point mutations in cells. In this work, we provide an in vitro characterization (UV and fluorescence spectroscopy, gel electrophoresis and nuclease assays) of the structure and stability of two repair-PPRH oligonucleotides and of the complexes they form with their single-stranded targets. We show that one PPRH oligonucleotide forms a hairpin, while the other folds, in potassium, into a guanine-quadruplex (G4). However, the hairpin-prone oligonucleotide does not form a triplex with its single-stranded target, while the G4-prone oligonucleotide converts from a G4 into a reverse-Hoogsteen hairpin forming a triplex with its target sequence. Our work proves, in particular, that folding of a PPRH oligonucleotide into a G4 does not necessarily impair sequence-specific DNA recognition by triplex formation. It also illustrates an original example of DNA structural conversion of a G4 into a reverse-Hoogsteen hairpin driven by triplex formation; this kind of conversion might occur at particular loci of genomic DNA.
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It is part of: Scientific Reports, 2017, vol. 7 , num. 39898
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ISSN: 2045-2322
Appears in Collections:Articles publicats en revistes (Bioquímica i Fisiologia)

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