The effect of L-thymidine, acyclic thymine and 8-bromoguanine on the stability of model G-quadruplex structures
The effect of L-thymidine, acyclic thymine and 8-bromoguanine on the stability of model G-quadruplex structures
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DOI：
10.1016/j.bbagen.2016.09.030
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发表时间：
2017-05-01
影响因子：
3
通讯作者：
Eritja, Ramon
中科院分区：
文献类型：
--
作者：
Avino, Anna;Mazzini, Stefania;Eritja, Ramon
背景资料：富含鸟嘌呤的寡核苷酸能够形成被称为G-四链体的四螺旋结构，具有有趣的生物学特性。方法：化学合成修饰的寡核苷酸，用光谱技术测定修饰后的G-四链体的相对稳定性。通过核磁共振进一步表征双8-BrdG修饰的四链体。结果：8-溴G取代的四链体与凝血酶的结合稳定性最高，而8-溴G取代的四链体与凝血酶的结合稳定性最高。NMR研究表明，TBA中的8-溴G修饰与环和四联体之间存在紧密的关系。结论：除T7位的单一修饰外，GNAT对环位置的取代均影响TBA的稳定性。单个L-胸苷取代产生TBA的不稳定。使用8-溴G观察到四链体稳定性的较大变化，发现在鸟嘌呤残基处修饰的凝血酶结合适体中发现的具有最高热稳定性的单一取代，并且对凝血酶具有良好的亲和力。双8-BrdG修饰在不同的四联体的反位置产生一个构象翻转从顺式到反式构象的8-Br-dG，有利于环-四联体相互作用，并保持整体TBA stability.General意义：修饰的富含鸟嘌呤的寡核苷酸是有价值的工具，用于寻找具有更高的热稳定性的G-四链体结构，并可能提供有趣的蛋白质-核酸结合特性的化合物。这篇文章是题为“G-四倍体”的特刊的一部分，客座编辑：康塞塔·吉安科拉博士和丹妮拉·蒙特萨奇奥博士。(C)© 2016 Elsevier B. V.版权所有。
Background: Guanine-rich oligonucleotides are capable of forming tetrahelical structures known as G-quadruplexes with interesting biological properties. We have investigated the effects of site-specific substitution in the loops and in the tetrads model G-quadruplexes using thymine glycol nucleic acid (GNA) units, L-thymidine and 8-Br-2'-deoxyguanosine.Methods: Modified oligonucleotides were chemically synthesized and spectroscopic techniques were used to determine the relative stability of the modified G-quadruplex. The double 8-BrdG-modified quadruplexes were further characterized by Nuclear Magnetic Resonance. Binding to thrombin of selected quadruplex was analyzed by gel electrophoresis retention assay.Results: The most interesting results were found with a 8-bromoG substitution that had the larger stabilization of the quadruplex. NMR studies indicate a tight relationship between the loops and the tetrads to accommodate 8-bromoG modifications within the TBA.Conclusions: The substitutions of loop positions with GNAT affect the TBA stability except for single modification in T7 position. Single L-thymidine substitutions produced destabilization of TBA. Larger changes on quadruplex stability are observed with the use of 8-bromoG finding a single substitution with the highest thermal stabilization found in thrombin binding aptamers modified at the guanine residues and having good affinity for thrombin. Double 8-BrdG modification in anti positions of different tetrads produce a conformational flip from syn to anti conformation of 8-Br-dG to favor loop-tetrad interaction and preserve the overall TBA stability.General significance: Modified guanine-rich oligonucleotides are valuable tools for the search for G-quadruplex structures with higher thermal stability and may provide compounds with interesting protein-nucleic acid binding properties. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio. (C) 2016 Elsevier B.V. All rights reserved.