Photocontrol of Genomic DNA Conformation by Using a Photosensitive Gemini Surfactant: Binding Affinity versus Reversibility
Photocontrol of Genomic DNA Conformation by Using a Photosensitive Gemini Surfactant: Binding Affinity versus Reversibility
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DOI：
10.1002/cbic.200800235
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发表时间：
2008-10-13
期刊：
影响因子：
3.2
通讯作者：
Baigl, Damien
中科院分区：
文献类型：
--
作者：
Geoffroy, Marie;Faure, Delphine;Baigl, Damien
在自然界中，基因组DNA是长分子，其被压缩以适合于狭窄的空间，例如真核细胞中的病毒衣壳或细胞核。此外，基因表达受到DNA或染色质的高级结构的强烈影响已经得到很好的证实。[1]因此，已经开发了几种策略来控制体外DNA构象和压实。它们中的大多数依赖于使用带相反电荷的化合物来中和DNA负电荷（例如，聚胺、表面活性剂、聚合物、纳米颗粒）。[2]最近，Le Ny和Lee提出了一种通过光控制基因组DNA构象的新方法[3]，我们将该系统应用于细胞模拟微环境内单分子水平的DNA构象控制。[4]该方法包括向DNA溶液中加入偶氮苯三甲基溴化铵（AzoTAB）。AzoTAB是一种阳离子表面活性剂，在365 nm处发生反式到顺式异构化，并伴随极性变化。因此，存在基因组DNA在黑暗条件下被压缩但在365 nm的UV照射下展开的AzoTAB浓度范围。然而，AzoTAB对DNA的亲和力非常低，也就是说，需要非常高浓度的AzoTAB来压实DNA。在此，我们首次使用光敏双子表面活性剂（AzoGEM）[5]通过光来控制DNA构象。我们发现AzoGEM与DNA强烈相互作用，允许在非常低的AzoGEM浓度下光控制构象。与AzoTAB相反，AzoGEM提供的DNA构象的光控制在DNA存在下不可逆。
In nature, genomic DNAs are long molecules that are compacted to fit within narrow spaces such as viral capsids or nuclei in eukaryotic cells. Moreover, it has been well established that gene expression is strongly affected by the higherorder structure of DNA or chromatin.[1] Several strategies have thus been developed to control DNA conformation and compaction in vitro. Most of them rely on the use of oppositely charged compounds to neutralize DNA negative charge (for example, polyamines, surfactants, polymers, nanoparticles).[2] Recently, Le Ny and Lee proposed a new methodology to control the conformation of genomic DNA by light [3] and we applied this system to the control of the DNA conformation at the single-molecule level inside cell-mimicking microenvironments.[4] This methodology consists of adding azobenzene trimethylammonium bromide (AzoTAB) to the DNA solution. AzoTAB is a cationic surfactant, which undergoes a trans to cis isomerization at 365 nm accompanied by a change of polarity. Consequently, there exists an AzoTAB concentration range for which genomic DNA is compacted under dark conditions but unfolded under UV illumination at 365 nm. However, the affinity of AzoTAB for DNA is very low, that is, a very high concentration of AzoTAB is needed to compact DNA. Herein we used for the first time a photosensitive gemini surfactant (AzoGEM)[5] to control DNA conformation by light. We found that AzoGEM interacts strongly with DNA, allowing photocontrol of conformation at a very low AzoGEM concentration. Contrary to AzoTAB, the photocontrol of DNA conformation provided by AzoGEM is not reversible in the presence of DNA.