Simonsson T, Sjöback R
Department of Biochemistry, Lundberg Institute, Chalmers University of Technology, Box 462, SE 405 30 Göteborg, Sweden.
J Biol Chem. 1999 Jun 11;274(24):17379-83. doi: 10.1074/jbc.274.24.17379.
It is emerging that DNA tetraplexes are pivotal for many major cellular processes, and techniques that assess their structure and nature to the point are under development. Here we show how the structural conversion of largely unstructured single-stranded DNA molecules into compact intrastrand DNA tetraplexes can be monitored by fluorescence resonance energy transfer. We recently reported that intrastrand tetraplex formation takes place in a nuclease hypersensitive element upstream of the human c-myc proto-oncogene. Despite the highly repetitive guanine-rich sequence of the hypersensitive element, fluorescence resonance energy transfer measurements indicate that only one well defined tetraplex structure forms therein. The proposed structure, which is specifically stabilized by potassium ions in vitro, has a core of three stacked guanine tetrads that is capped by two intrastrand A-T base pairs.
越来越多的证据表明，DNA四链体对许多主要细胞过程至关重要，目前正在开发能够精确评估其结构和性质的技术。在这里，我们展示了如何通过荧光共振能量转移来监测大部分无结构的单链DNA分子向紧密的链内DNA四链体的结构转变。我们最近报道，链内四链体的形成发生在人类c-myc原癌基因上游的核酸酶高敏元件中。尽管该高敏元件富含鸟嘌呤且序列高度重复，但荧光共振能量转移测量表明，其中仅形成一种明确的四链体结构。所提出的结构在体外由钾离子特异性稳定，其核心是三个堆叠的鸟嘌呤四联体，由两个链内A-T碱基对封顶。
