BINDING OF TRIPLE HELIX FORMING OLIGONUCLEOTIDES TO SITES IN GENE PROMOTERS
BINDING OF TRIPLE HELIX FORMING OLIGONUCLEOTIDES TO SITES IN GENE PROMOTERS
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DOI：
10.1021/bi00102a017
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发表时间：
1991-09-24
期刊：
影响因子：
2.9
通讯作者：
HOGAN, ME
中科院分区：
文献类型：
--
作者：
DURLAND, RH;KESSLER, DJ;HOGAN, ME
描述了一类形成三链体的寡脱氧核糖核苷酸 (TFO)，在镁存在的情况下，它可以在生理 pH 值下与双链体 DNA 中天然存在的位点结合。这些数据与 TFO 结合在双链 DNA 大沟中形成三链复合物的结构一致，该复合物表面上与先前描述的三链体相似。这类三链体的显着特征是 TFO 结合显然涉及氢键 G.GC 和 T.AT 三联体的形成，并且 TFO 与下面双链体中更富含嘌呤的链反向平行结合。描述了三个不同基因的启动子区域中的靶标的三链体形成：人类c-myc和表皮生长因子受体基因以及小鼠胰岛素受体基因。所有三个位点都相对富含 GC，并且在一条链上具有高比例的嘌呤残基。 DNase I 足迹显示，在毫摩尔浓度的镁存在下，单个 TFO 在 pH 7.4-7.8 下选择性地结合到其靶位点。三链体形成的电泳分析表明，特定的 TFO 与其靶位点结合，表观解离常数在 10(-7)-10(-9) M 范围内。通过将曙红或铁螯合基团附着到 TFO 的一端并监测结合的双链 DNA 的损伤模式来确认结合的 TFO 的链方向。讨论了可能的氢键模式和三链体结构。
A class of triplex-forming oligodeoxyribonucleotides (TFOs) is described that can bind to naturally occurring sites in duplex DNA at physiological pH in the presence of magnesium. The data are consistent with a structure in which the TFO binds in the major groove of double-stranded DNA to form a three-stranded complex that is superficially similar to previously described triplexes. The distinguishing features of this class of triplex are that TFO binding apparently involves the formation of hydrogen-bonded G.GC and T.AT triplets and the TFO is bound antiparallel with respect to the more purine-rich strand of the underlying duplex. Triplex formation is described for targets in the promoter regions of three different genes: the human c-myc and epidermal growth factor receptor genes and the mouse insulin receptor gene. All three sites are relatively GC rich and have a high percentage of purine residues on one strand. DNase I footprinting shows that individual TFOs bind selectively to their target sites at pH 7.4-7.8 in the presence of millimolar concentrations of magnesium. Electrophoretic analysis of triplex formation indicates that specific TFOs bind to their target sites with apparent dissociation constants in the 10(-7)-10(-9) M range. Strand orientation of the bound TFOs was confirmed by attaching eosin or an iron-chelating group to one end of the TFO and monitoring the pattern of damage to the bound duplex DNA. Possible hydrogen-bonding patterns and triplex structures are discussed.