Deconvoluting the structural and drug-recognition complexity of the G-quadruplex-forming region upstream of the bcl-2 P1 promoter
Deconvoluting the structural and drug-recognition complexity of the G-quadruplex-forming region upstream of the bcl-2 P1 promoter
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DOI：
10.1021/ja0563861
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发表时间：
2006-04-26
影响因子：
15
通讯作者：
Hurley, LH
中科院分区：
文献类型：
--
作者：
Dexheimer, TS;Sun, D;Hurley, LH
人bcl-2基因在P1启动子上游含有一个富含GC的区域，该区域已被证明与bcl-2基因表达的调控密切相关。我们已经证明，在这个区域中的DNA的鸟嘌呤丰富的链可以形成三个不同的分子内G-四链体结构中的任何一个。突变和缺失分析允许分离和鉴定三个重叠的DNA序列在这个元素，形成了三个单独的G-四链体。每一个这些特点是使用非变性凝胶分析，DMS足迹，和圆二色性。中心的G-四链体是最稳定的，它形成了一个混合的平行/反平行结构，由三个四联体组成，这些四联体由一个、七个和三个碱基的环连接。发现三种不同的G-四链体相互作用剂进一步稳定这些结构，对这些G-四链体中的一种或多种具有单独的选择性。总的来说，这些结果表明，在bc/-2基因的启动子区域中鉴定的多个G-四链体可能发挥与c-myc启动子中的G-四链体类似的作用，因为它们的形成可以用于调节基因转录。最后，我们证明了在bcl-2启动子中的G-四链体的复杂性超出了形成三个单独的G-四链体中的任何一个的能力，每个G-四链体都有能力形成三个或六个不同的环异构体。这些结果进行了讨论，在此G-四链体形成元件在bcl-2基因表达的调制和固有的复杂性的系统中，不同的G-四链体和环异构体是可能的生物学意义。
The human bcl-2 gene contains a GC-rich region upstream of the P1 promoter that has been shown to be critically involved in the regulation of bcl-2 gene expression. We have demonstrated that the guanine-rich strand of the DNA in this region can form any one of three distinct intramolecular G-quadruplex structures. Mutation and deletion analysis permitted isolation and identification of three overlapping DNA sequences within this element that formed the three individual G-quadruplexes. Each of these was characterized using nondenaturing gel analysis, DMS footprinting, and circular dichroism. The central G-quadruplex, which is the most stable, forms a mixed parallel/antiparallel structure consisting of three tetrads connected by loops of one, seven, and three bases. Three different G-quadruplex-interactive agents were found to further stabilize these structures, with individual selectivity toward one or more of these G-quadruplexes. Collectively, these results suggest that the multiple G-quadruplexes identified in the promoter region of the bc/-2 gene are likely to play a similar role to the G-quadruplexes in the c-myc promoter in that their formation could serve to modulate gene transcription. Last, we demonstrate that the complexity of the G-quadruplexes in the bcl-2 promoter extends beyond the ability to form any one of three separate G-quadruplexes to each having the capacity to form either three or six different loop isomers. These results are discussed in relation to the biological significance of this G-quadruplex-forming element in modulation of bcl-2 gene expression and the inherent complexity of the system where different G-quadruplexes and loop isomers are possible.