SAM‐II Riboswitch Samples at least Two Conformations in Solution in the Absence of Ligand: Implications for Recognition
| Autor: | Bin Chen, T. Kwaku Dayie, Regan M. LeBlanc |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Riboswitch
0301 basic medicine Stereochemistry Metabolite Proton Magnetic Resonance Spectroscopy Ligands 010402 general chemistry 01 natural sciences Catalysis chemistry.chemical_compound 03 medical and health sciences Carbon-13 Magnetic Resonance Spectroscopy Conformational isomerism Chemistry Ligand Chemical shift RNA General Chemistry Nuclear magnetic resonance spectroscopy General Medicine 0104 chemical sciences Crystallography 030104 developmental biology Saturation transfer Nucleic Acid Conformation |
| Zdroj: | Angewandte Chemie. 128:2774-2777 |
| ISSN: | 1521-3757 0044-8249 |
| Popis: | Conformational equilibria are increasingly recognized as pivotal for biological function. Traditional structural analyses provide a static image of conformers in solution that sometimes present conflicting views. From (13) C and (1) H chemical exchange saturation transfer experiments, in concert with ligation and selective labeling strategies, we show that in the absence of metabolite, a Mg(2+) (0-0.5 mm)-bound apo SAM-II riboswitch RNA exists in a minor (≈10 %) partially closed state that rapidly exchanges with a predominantly (≈90 %) open form with a lifetime of ≈32 ms. The base and sugar (H6,C6, H1',C1') chemical shifts of C43 for the dominant conformer are similar to those of a free CMP, but those of the minor apo species are comparable to shifts of CMPs in helical RNA regions. Our results suggest that these transient, low populated states stabilized by Mg(2+) will likely enhance rapid ligand recognition and, we anticipate, will play potentially ubiquitous roles in RNA signaling. |
| Databáze: | OpenAIRE |
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