Details

Autor(en) / Beteiligte

• McKinney, S A
• Tan, E
• Wilson, T J
• Nahas, M K
• Déclais, A-C
• Clegg, R M
• Lilley, D M J
• Ha, T

Titel

Single-molecule studies of DNA and RNA four-way junctions

Ist Teil von

• Biochemical Society transactions, 2004-02, Vol.32 (Pt 1), p.41

Ort / Verlag

England

Erscheinungsjahr

2004

Quelle

MEDLINE

Beschreibungen/Notizen

• Branched helical junctions are common in nucleic acids. In DNA, the four-way junction (Holliday junction) is an essential intermediate in homologous recombination and is a highly dynamic structure, capable of stacking conformer transitions and branch migration. Our single-molecule fluorescence studies provide unique insight into the energy landscape of Holliday junctions by visualizing these processes directly. In the hairpin ribozyme, an RNA four-way junction is an important structural element that enhances active-site formation by several orders of magnitude. Our single-molecule studies suggest a plausible mechanism for how the junction achieves this remarkable feat; the structural dynamics of the four-way junction bring about frequent contacts between the loops that are needed to form the active site. The most definitive evidence for this is the observation of three-state folding in single-hairpin ribozymes, the intermediate state of which is populated due to the intrinsic properties of the junction.