DNA Repair by DNA: The UV1C DNAzyme Catalyzes Photoreactivation of Cyclobutane Thymine Dimers in DNA More Effectively than Their de Novo Formation
DNA Repair by DNA: The UV1C DNAzyme Catalyzes Photoreactivation of Cyclobutane Thymine Dimers in DNA More Effectively than Their de Novo Formation
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DOI：
10.1021/acs.biochem.6b00951
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发表时间：
2016-11-01
期刊：
影响因子：
2.9
通讯作者：
Sen, Dipankar
中科院分区：
文献类型：
--
作者：
Barlev, Adam;Sekhon, Gurpreet S.;Sen, Dipankar
UV 1C是一种42-nt DNA寡核苷酸，是一种脱氧核酶（DNAzyme），最佳使用305 nm波长的光催化置于有间隙的非天然DNA底物TDP内的环丁烷胸腺嘧啶二聚体的光复活。在这里，我们表明，UV 1C也能够photoreactivating胸腺嘧啶二聚体内的一个真实的单链DNA基板，LDP。这种真正的UV 1C底物，使第一次，调查是否UV 1C催化光复活或从头形成的胸腺嘧啶二聚体。与LDP和UV 1C进行的单周转实验，相对于LDP单独在单链和双链背景下的对照实验，表明UV 1C适度促进胸腺嘧啶二聚体的形成，其主要活动确实是光复活。LDP在三种情况下达到不同的光稳态：作为单链，作为双螺旋的组成部分，以及作为与UV 1C的1：1复合物。上述关于催化DNA的辅因子独立的光复活能力的结果加强了一系列最近的、意想不到的报道，即纯粹基于核苷酸的光复活在常规双螺旋DNA内也是可操作的。
UV1C, a 42-nt DNA oligonucleotide, is a deoxyribozyme (DNAzyme) that optimally uses 305 nm wavelength light to catalyze photoreactivation of a cyclobutane thymine dimer placed within a gapped, unnatural DNA substrate, TDP. Herein we show that UV1C is also capable of photoreactivating thymine dimers within an authentic single-stranded DNA substrate, LDP. This bona fide UV1C substrate enables, for the first time, investigation of whether UV1C catalyzes only photoreactivation or also the de novo formation of thymine dimers. Single-turnover experiments carried out with LDP and UV1C, relative to control experiments with LDP alone in single-stranded and double-stranded contexts, show that while UV1C does modestly promote thymine dimer formation, its major activity is indeed photoreactivation. Distinct photostationary states are reached for LDP in its three contexts: as a single strand, as a constituent of a double-helix, and as a 1:1 complex with UV1C. The above results on the cofactor-independent photoreactivation capabilities of a catalytic DNA reinforce a series of recent, unexpected reports that purely nucleotide-based photoreactivation is also operational within conventional double-helical DNA.