Punt Philip M, Clever Guido H
TU Dortmund University , Faculty for Chemistry and Chemical Biology , Otto-Hahn-Str. 6 , 44227 Dortmund , Germany . Email:
Chem Sci. 2019 Jan 7;10(8):2513-2518. doi: 10.1039/c8sc05020a. eCollection 2019 Feb 28.
Four imidazoles, serving as metalloprotein-inspired ligands for complexing a range of transition metal cations, were incorporated into tetramolecular G-quadruplex DNA structures. Modified quadruplexes were found to complex Cu(ii), Ni(ii), Zn(ii) and Co(ii) in a 1 : 1 ratio with unprecedented strong thermal stabilizations of up to Δ = +51 °C. Furthermore, addition of Cu(ii) was found to lead to extraordinarily fast G-quadruplex association rates with values being ∼100 times higher compared to unmodified G-quadruplexes. This is ascribed to a template effect of Cu(ii), preorganizing the four single strands coordination, followed by rapid formation of hydrogen-bonded G-quartets. Native electrospray ionization mass spectrometry (ESI), coupled with trapped ion-mobility spectrometry (timsTOF), supports the proposed 1 : 1 G-quadruplex-metal complexes and could further disclose their ability to bind the iron-porphyrin complex hemin in a 1 : 1 stoichiometry. DNA sequence design allowed us to equip this G-quadruplex-hemin complex, known to function as a horseradish peroxidase mimic, with a metal-dependent trigger. A competitive screen of transition metals revealed a high selectivity for Cu(ii), even in mixtures of several divalent metal cations. Once formed, the Cu(ii)-carrying DNAzyme was shown to be preserved in the presence of EDTA, attributed to its remarkable kinetic stability. Stimuli-responsive G-quadruplexes promise application in DNAzymes with switchable activity, adaptive sensors and dynamic DNA origami constructs.
四种咪唑作为受金属蛋白启发的配体，用于络合一系列过渡金属阳离子，被引入到四分子G-四链体DNA结构中。发现修饰后的四链体能够以1:1的比例络合Cu(ii)、Ni(ii)、Zn(ii)和Co(ii)，热稳定性前所未有的强，高达Δ = +51°C。此外，发现添加Cu(ii)会导致G-四链体的缔合速率极快，其值比未修饰的G-四链体高约100倍。这归因于Cu(ii)的模板效应，它预先组织了四条单链的配位，随后快速形成氢键连接的G-四重体。原生电喷雾电离质谱(ESI)与捕集离子淌度质谱(timsTOF)联用，支持了所提出的1:1 G-四链体-金属络合物，并能进一步揭示它们以1:1化学计量比结合铁卟啉络合物血红素的能力。DNA序列设计使我们能够为这种已知具有辣根过氧化物酶模拟功能的G-四链体-血红素络合物配备一个金属依赖性触发因子。对过渡金属的竞争性筛选显示，即使在几种二价金属阳离子的混合物中，对Cu(ii)也有很高的选择性。一旦形成，携带Cu(ii)的DNAzyme在EDTA存在下仍能保持稳定，这归因于其显著的动力学稳定性。刺激响应性G-四链体有望应用于具有可切换活性的DNAzyme、自适应传感器和动态DNA折纸结构中。
