Elongated Thrombin Binding Aptamer: A G-Quadruplex Cation-Sensitive Conformational Switch
Elongated Thrombin Binding Aptamer: A G-Quadruplex Cation-Sensitive Conformational Switch
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DOI：
10.1002/chem.201103381
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发表时间：
2012-04-01
影响因子：
4.3
通讯作者：
Buess-Herman, Claudine
中科院分区：
文献类型：
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作者：
De Rache, Aurore;Kejnovska, Iva;Buess-Herman, Claudine
基于核酸适体的生物传感器为蛋白质的高性能、特异性检测提供了很好的前景。凝血酶结合适体（TBA）是一种形成G-四链体的DNA序列，其通常在一端延长以增加其在生物传感器配置中的分析性能。在此，我们研究TBA在其5'端的延长如何影响其结构和稳定性。圆二色性光谱显示TBA与所有研究的阳离子（Ba 2+、Ca 2+、K+、Mg 2+、Na+、NH 4+、Sr 2+和[Ru（NH 3）6]2+/3+氧化还原标记物）以反平行的G-四链体构象折叠，而在这些阳离子中的一些阳离子的存在下，伸长的适体采用其他结构。基于UV光谱熔解曲线评价每种结构的稳定性。热差光谱证实了所有构象的四重特征。延长的序列可以采用平行或反平行结构，这取决于阳离子的性质;这可以潜在地赋予离子敏感的开关行为。这种开关性质是证明与常用的氧化还原络合物[Ru（NH 3）6]3+，它诱导的平行构象在非常低的浓度（10当量每条链）。大量K+的加入使构象恢复为反平行形式，并为电化学生物传感或氧化还原活性响应装置打开了有趣的前景。
Aptamer-based biosensors offer promising perspectives for high performance, specific detection of proteins. The thrombin binding aptamer (TBA) is a G-quadruplex-forming DNA sequence, which is frequently elongated at one end to increase its analytical performances in a biosensor configuration. Herein, we investigate how the elongation of TBA at its 5' end affects its structure and stability. Circular dichroism spectroscopy shows that TBA folds in an antiparallel G-quadruplex conformation with all studied cations (Ba2+, Ca2+, K+, Mg2+, Na+, NH4+, Sr2+ and the [Ru(NH3)6]2+/3+ redox marker) whereas other structures are adopted by the elongated aptamers in the presence of some of these cations. The stability of each structure is evaluated on the basis of UV spectroscopy melting curves. Thermal difference spectra confirm the quadruplex character of all conformations. The elongated sequences can adopt a parallel or an antiparallel structure, depending on the nature of the cation; this can potentially confer an ion-sensitive switch behavior. This switch property is demonstrated with the frequently employed redox complex [Ru(NH3)6]3+, which induces the parallel conformation at very low concentrations (10 equiv per strand). The addition of large amounts of K+ reverts the conformation to the antiparallel form, and opens interesting perspectives for electrochemical biosensing or redox-active responsive devices.