OLIGONUCLEOTIDE-DIRECTED TRIPLE HELIX FORMATION AT ADJACENT OLIGOPURINE AND OLIGOPYRIMIDINE DNA TRACTS BY ALTERNATE STRAND RECOGNITION
OLIGONUCLEOTIDE-DIRECTED TRIPLE HELIX FORMATION AT ADJACENT OLIGOPURINE AND OLIGOPYRIMIDINE DNA TRACTS BY ALTERNATE STRAND RECOGNITION
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DOI：
10.1093/nar/20.20.5279
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发表时间：
1992-10-25
影响因子：
14.9
通讯作者：
JOHNSTON, BH
中科院分区：
文献类型：
--
作者：
JAYASENA, SD;JOHNSTON, BH
三链DNA实际应用的一个重要限制是它对靶DNA序列中的寡嘌呤序列的要求。通过允许第三链与交替链上的嘌呤配对，同时通过结合两大类碱基三联体Py来保持所需的链极性，三链形成序列的谱系可能扩展到相邻的嘌呤和嘧啶块。PuPy和Pu。帕皮。以这种方式形成三链DNA不需要在第三链上有不寻常的碱基或主干连接。这种方法以前已经被证明用于分子内络合物中5‘-(Pu)n(Py)n-3’类型的靶序列。利用亲和力切割和DNase I足迹技术，我们发现在5‘-(Pu)n(Py)n-3’和5‘-(Py)n(Pu)n-3’靶序列上也可以形成分子间三链。然而，在5‘-(Py)n(Pu)n-3’序列上形成三链的产率较低。即使在酸性pH下，当需要大量连续的C+.GC碱基三联体时，也不赞成形成三联体。这些结果表明，在由嘌呤和嘧啶组成的序列上通过交替链识别形成三链可能是普遍可行的。
A significant limitation to the practical application of triplex DNA is its requirement for oligopurine tracts in target DNA sequences. The repertoire of triplex-forming sequences can potentially be expanded to adjacent blocks of purines and pyrimidines by allowing the third strand to pair with purines on alternate strands, while maintaining the required strand polarities by combining the two major classes of base triplets, Py . PuPy and Pu . PuPy. The formation of triplex DNA in this fashion requires no unusual bases or backbone linkages on the third strand. This approach has previously been demonstrated for target sequences of the type 5'-(Pu)n(Py)n-3' in intramolecular complexes. Using affinity cleaving and DNase I footprinting, we show here that intermolecular triplexes can also be formed at both 5'-(Pu)n(PY)n-3' and 5'-(Py)n(Pu)n-3' target sequences. However, triplex formation at a 5'-(Py)n(Pu)n-3' sequence occurs with lower yield. Triplex formation is disfavored, even at acid pH, when a number of contiguous C+ .GC base triplets are required. These results suggest that triplex formation via alternate strand recognition at sequences made up of blocks of purines and pyrimidines may be generally feasible.