Base dynamics in a UUCG tetraloop RNA hairpin characterized by (15)N spin relaxation: Correlations with structure and stability Journal Article
| Authors: | Akke, M.; Fiala, R.; Jiang, F.; Patel, D.; Palmer, A. G. 3rd |
| Article Title: | Base dynamics in a UUCG tetraloop RNA hairpin characterized by (15)N spin relaxation: Correlations with structure and stability |
| Abstract: | Intramolecular dynamics of guanine and uracil bases in a 14-nt RNA hairpin including the extraordinarily stable UUCG tetraloop were studied by N-15 spin relaxation experiments that are sensitive to structural fluctuations occurring on a time scale of picoseconds to nanoseconds. The relaxation data were interpreted in the framework of the anisotropic model-free formalism, using assumed values for the chemical shift anisotropies of the N-15 spins. The rotational diffusion tensor was determined to be symmetric with an axial ratio of 1.34 +/- 0.12, in agreement with estimates based on the ratio of the principal moments of the inertia tenser. The model-free results indicate that the bases of the G-U pair in the tetraloop are at least as rigid as the interior base pairs in the stem, whereas the 5'-terminal guanine is more flexible. The observed range of order parameters corresponds to base fluctuations of 19-22 degrees about the chi torsion angle. The results reveal dynamical consequences of the unusual structural features in the UUCG tetraloop and offer insights into the configurational entropy of hairpin formation. |
| Keywords: | proteins; spectroscopy; acids; entropy; free-energy; order parameter; backbone dynamics; model-free approach; anisotropic rotational diffusion; conformational fluctuations; unusually stable rna; nuclear magnetic-relaxation; nmr order parameters; dna hairpins |
| Journal Title: | RNA |
| Volume: | 3 |
| Issue: | 7 |
| ISSN: | 1355-8382 |
| Publisher: | Cold Spring Harbor Laboratory Press |
| Date Published: | 1997-07-01 |
| Start Page: | 702 |
| End Page: | 709 |
| Language: | English |
| ACCESSION: | WOS:A1997XH28300003 |
| PROVIDER: | wos |
| PMCID: | PMC1369518 |
| PUBMED: | 9214654 |
| Notes: | Article -- Source: Wos |
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