| Attributs | Valeurs |
|---|
| type
| |
| Is Part Of
| |
| Subject
| |
| Title
| - Kinetics of RNA Refolding in Dynamic Equilibrium by1H-Detected 15N Exchange NMR Spectroscopy
|
| has manifestation of work
| |
| related by
| |
| Author
| |
| Abstract
| - By implementing new NMR methods that were designed to map very slow exchange processeswe have investigated and characterized the refolding kinetics of a thermodynamically stable 34mer RNAsequence in dynamic equilibrium. The RNA sequence was designed to undergo a topologically favoredconformational exchange between different hairpin folds, serving as a model to estimate the minimal timerequired for more complex RNA folding processes. Chemically prepared RNA sequences with sequence-selective 15N labels provided the required signal separation and allowed a straightforward signal assignmentof the imino protons by HNN correlation experiments. The 2D version of the new 1H-detected 15N exchangespectroscopy (EXSY) pulse sequence provided cross-peaks for resonances belonging to different foldsthat interchange on the time scale of longitudinal relaxation of 15N nuclei bound to imino protons. The34mer RNA sequence exhibits two folds which exchange on the observable time scale (τobs ≈ T1{15Ν} <5 s) and a third fold which is static on this time scale. A 1D version of the 15N exchange experiment allowedthe measurement of the exchange rates between the two exchanging folds as a function of temperatureand the determination of the corresponding activation energies Ea and frequency factors A. We found thatthe refolding rates are strongly affected by an entropically favorable preorientation of the replacing strand.The activation energies are comparable to values obtained for the slow refolding of RNA sequences ofsimilar thermodynamic stability but less favorable topology.
|
| article type
| |
| is part of this journal
| |
