Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA.
Sci Rep. 2018 Jul 4;8(1):10115. doi: 10.1038/s41598-018-28572-x.
The GTGTGTG (G3T) sequence folds into a monomolecular quadruplex with all-parallel G segments connected to each other by chain-reversal loops. The homopolymer consisting of n number of G3T domains directly conjugated to each other folds into an uninterrupted and unusually stable polymer, tetrahelical monomolecular DNA (tmDNA). It was demonstrated that the tmDNA architecture has strong potential in nanotechnologies as highly programmable building material, high affinity coupler and the driving force for endergonic reactions. Here, we explore capability of analogous DNA sequences (i.e., monomolecular quadruplexes with G or G segments) to construct tmDNA architecture. The study demonstrates that tmDNA can have only one building pattern based on a quadruplex domain with three G-tetrads and single-nucleotide loops, G3N (N = G, A, C and T); all other domains demonstrate antiparallel topologies unsuitable for tmDNA. The present study also suggests that polyguanine is capable of tmDNA formation with strictly defined building pattern; G segments connected to each other by chain-reversal G-loops. These findings can have significant impact on (i) DNA nanotechnologies; (ii) structure prediction of G-rich sequences of genome; and (iii) modeling of abiogenesis.
GTGTGTG（G3T）序列折叠成一个具有所有平行 G 片段的单分子四链体，通过链反转环彼此连接。由 n 个直接连接在一起的 G3T 结构域组成的同聚物折叠成一个不间断且异常稳定的聚合物，即四螺旋单分子 DNA（tmDNA）。已经证明，tmDNA 结构具有作为高度可编程建筑材料、高亲和偶联物和内禀反应驱动力的强大潜力。在这里，我们探索了类似的 DNA 序列（即具有 G 或 G 片段的单分子四链体）构建 tmDNA 结构的能力。该研究表明，tmDNA 只能基于具有三个 G-四联体和单核苷酸环的四链体结构域具有一种构建模式，G3N（N=G、A、C 和 T）；所有其他结构域都表现出不适合 tmDNA 的反平行拓扑结构。本研究还表明，聚鸟嘌呤能够形成具有严格定义的构建模式的 tmDNA；通过链反转 G-环彼此连接的 G 片段。这些发现可能对（i）DNA 纳米技术；（ii）基因组中富含 G 序列的结构预测；和（iii）无生源说的建模产生重大影响。
