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Updated: Aug 15, 2026

Studying DNA Looping by Single-Molecule FRET
Published on: June 28, 2014
Stem-loop oligonucleotides as tools for labelling double-stranded DNA
Bénédicte Géron-Landre1, Thibaut Roulon, Christophe Escudé
1Laboratoire Régulation et Dynamique des Génomes, Département Régulations, Développement et Diversité Moléculaire, Muséum National d'Histoire Naturelle, Paris Cedex, France.
Abstract:
We report on a sequence-specific double-stranded DNA labelling strategy in which a stem-loop triplex forming oligonucleotide (TFO) is able to encircle its DNA target. Ligation of this TFO to either a short hairpin oligonucleotide or a long double-stranded DNA fragment leads to the formation of a topological complex. This process requires the hybridization of both extremities of the TFO to each other on a few base pairs. The effects of different factors on the formation of these complexes have been investigated. Efficient complex formation was observed using both GT or TC TFOs. The stem-loop structure enhances the specificity of the complex. The topologically linked TFO remains associated with its target even under conditions that do not favour triple-helix formation. This approach is sufficiently sensitive for detection of a 20-bp target sequence at the subfemtomolar level. This study provides new insights into the mechanics and properties of stem-loop TFOs and their complexes with double-stranded DNA targets. It emphasizes the interest of such molecules in the development of new tools for the specific labelling of short DNA sequences.
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