Reuss Andreas J, Vogel Marc, Weigand Julia E, Suess Beatrix, Wachtveitl Josef
Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Frankfurt, Germany.
Department of Biology, Technical University of Darmstadt, Darmstadt, Germany.
Biophys J. 2014 Dec 16;107(12):2962-2971. doi: 10.1016/j.bpj.2014.11.001.
Synthetic riboswitches are versatile tools for the study and manipulation of biological systems. Yet, the underlying mechanisms governing its structural properties and regulation under physiological conditions are poorly studied. We performed spectroscopic and calorimetric experiments to explore the folding kinetics and thermodynamics of the tetracycline-binding aptamer, which can be employed as synthetic riboswitch, in the range of physiological magnesium concentrations. The dissociation constant of the ligand-aptamer complex was found to strongly depend on the magnesium concentration. At physiological magnesium concentrations, tetracycline induces a significant conformational shift from a compact, but heterogeneous intermediate state toward the completely formed set of tertiary interactions defining the regulation-competent structure. Thus, the switching functionality of the tetracycline-binding aptamer appears to include both a conformational rearrangement toward the regulation-competent structure and its thermodynamic stabilization.
合成核糖开关是用于研究和操纵生物系统的多功能工具。然而，在生理条件下控制其结构特性和调节的潜在机制却鲜有研究。我们进行了光谱和量热实验，以探索四环素结合适体（可作为合成核糖开关）在生理镁浓度范围内的折叠动力学和热力学。发现配体 - 适体复合物的解离常数强烈依赖于镁浓度。在生理镁浓度下，四环素诱导从紧密但异质的中间状态向定义调节活性结构的完全形成的三级相互作用组发生显著的构象转变。因此，四环素结合适体的开关功能似乎既包括向调节活性结构的构象重排及其热力学稳定。
