School of Fundamental Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand.
Org Biomol Chem. 2019 Apr 17;17(16):4031-4042. doi: 10.1039/c9ob00360f.
Here we demonstrate G-quadruplex formation by oligodeoxynucleotides containing α-2'-deoxyguanosine (α-dG) as a sole source of guanosines in G4T4, G4T4G4 and T(G3Tn)3G3T sequences with various numbers of natural β-T in the loops (n = 1-4). Based on circular dichroism spectra we observed that all α-dG-containing DNAs formed G-quadruplexes with uniform arrangement of α-dG-tetrads, which implies formation of G-quadruplexes of parallel topology. In several cases, native DNA structures that usually adopt an antiparallel topology were converted to more thermally stable G-quadruplexes of parallel topology. Using 2D ROESY NMR spectra a new 'sequential walk' was established for α-dGs in a tetramolecular, parallel complex formed by the α-G4β-T4 sequence. Analysis of ROEs in α-dGs indicates that guanines in [α-G4β-T4]4 adopt anti-glycosidic conformations. These results demonstrate that α-dG can be used for an antiparallel-to-parallel switch of G-quadruplex DNAs producing complexes with higher thermal stability and uniform stacking of α-dG-tetrads.
在这里，我们展示了含有α-2'-脱氧鸟苷（α-dG）的寡脱氧核苷酸形成 G-四链体的情况，这些寡脱氧核苷酸中只有α-dG 作为 G4T4、G4T4G4 和 T(G3Tn)3G3T 序列中鸟苷的唯一来源，其中环中的天然β-T 数量为 n = 1-4。根据圆二色光谱，我们观察到所有含α-dG 的 DNA 都形成了具有均匀排列的α-dG-四联体的 G-四链体，这意味着形成了具有平行拓扑结构的 G-四链体。在几种情况下，通常采用反平行拓扑结构的天然 DNA 结构被转化为更热稳定的具有平行拓扑结构的 G-四链体。使用 2D ROESY NMR 光谱，我们为α-G4β-T4 序列形成的四聚体、平行复合物中的α-dGs 建立了一个新的“顺序行走”。对α-dGs 中的 ROEs 的分析表明，[α-G4β-T4]4 中的鸟嘌呤采用反糖苷构象。这些结果表明，α-dG 可用于反平行到平行的 G-四链体 DNA 开关转换，产生具有更高热稳定性和均匀堆叠的α-dG-四联体的复合物。
