DNA double helices recognize mutual sequence homology in a protein free environment
DNA double helices recognize mutual sequence homology in a protein free environment
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DOI：
10.1021/jp7112297
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发表时间：
2008-01-31
影响因子：
3.3
通讯作者：
Kornyshev, Alexei A.
中科院分区：
文献类型：
--
作者：
Baldwin, Geoff S.;Brooks, Nicholas J.;Kornyshev, Alexei A.
DNA 双螺旋的结构和生物学功能基于识别两条 DNA 单链之间序列互补性的相互作用。单条 DNA 链也可以通过结合在双螺旋序列的凹槽中并形成三链体来识别双螺旋序列。我们现在发现，序列识别也发生在没有任何单链元件的完整 DNA 双链体之间。我们对两种荧光标记的双螺旋 DNA 分子的混合物进行了成像，这两种分子具有相同的核苷酸组成和长度（50% GC；294 个碱基对）但序列不同。在具有较小渗透压的电解溶液中，这些 DNA 形成离散的液晶聚集体（球晶）。我们观察到每个球晶内两种 DNA 的自发分离，这表明在没有蛋白质的情况下，核苷酸序列识别发生在被水分隔的双螺旋之间，这与我们之前的理论假设一致。因此，我们报告了实验证据并讨论了远距离识别同源 DNA 的可能机制。
The structure and biological function of the DNA double helix are based on interactions recognizing sequence complementarity between two single strands of DNA. A single DNA strand can also recognize the double helix sequence by binding in its groove and forming a triplex. We now find that sequence recognition occurs between intact DNA duplexes without any single-stranded elements as well. We have imaged a mixture of two fluorescently tagged, double helical DNA molecules that have identical nucleotide composition and length (50% GC; 294 base pairs) but different sequences. In electrolytic solution at minor osmotic stress, these DNAs form discrete liquid-crystalline aggregates (spherulites). We have observed spontaneous segregation of the two kinds of DNA within each spherulite, which reveals that nucleotide sequence recognition occurs between double helices separated by water in the absence of proteins, consistent with our earlier theoretical hypothesis. We thus report experimental evidence and discuss possible mechanisms for the recognition of homologous DNAs from a distance.