Covalent crosslinking of DNA strands provides a useful tool for medical, biochemical, and DNA nanotechnology applications. Here we present a light-induced interstrand DNA crosslinking reaction using the modified nucleoside 5-phenylethynyl-2′-deoxyuridine (^PhedU). The crosslinking ability of ^PhedU was programmed by base pairing and by metal ion interaction at the Watson–Crick base pairing site. Rotation to intrahelical positions was favored by hydrophobic stacking and enabled an unexpected photochemical alkene–alkyne [2 + 2] cycloaddition within the DNA duplex, resulting in efficient formation of a ^PhedU dimer after short irradiation times of a few seconds. A ^PhedU-dimer-containing DNA was shown to efficiently bind a helicase complex, but the covalent crosslink completely prevented DNA unwinding, suggesting possible applications in biochemistry or structural biology.

中文翻译：

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烯烃-炔烃 [2 + 2] 光环加成的可编程 DNA 链间交联

DNA 链的共价交联为医学、生物化学和 DNA 纳米技术应用提供了有用的工具。在这里，我们提出了使用修饰的核苷 5-苯基乙炔基-2'-脱氧尿苷 ( ^Phe dU) 的光诱导链间 DNA 交联反应。^Phe dU的交联能力通过碱基配对和 Watson-Crick 碱基配对位点的金属离子相互作用进行编程。疏水堆积有利于旋转到螺旋内位置，并在 DNA 双链体中实现意想不到的光化学烯烃-炔烃 [2 + 2] 环加成，从而在几秒的短照射时间后有效形成 Phe dU 二聚体^。苯^丙氨酸含有 dU-二聚体的 DNA 被证明可以有效地结合解旋酶复合物，但共价交联完全阻止了 DNA 解旋，表明在生物化学或结构生物学中的可能应用。