DNA UNWINDING UPON STRAND-DISPLACEMENT BINDING OF A THYMINE-SUBSTITUTED POLYAMIDE TO DOUBLE-STRANDED DNA
DNA UNWINDING UPON STRAND-DISPLACEMENT BINDING OF A THYMINE-SUBSTITUTED POLYAMIDE TO DOUBLE-STRANDED DNA
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DOI：
10.1073/pnas.90.5.1667
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发表时间：
1993-03-01
影响因子：
11.1
通讯作者：
NIELSEN, PE
中科院分区：
文献类型：
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作者：
CHERNY, DY;BELOTSERKOVSKII, BP;NIELSEN, PE
最近发现，由连接在氨乙基甘氨酸主链上的胸腺嘧啶组成的聚酰胺核酸（PNA）类似物能与寡核苷酸和双链DNA的腺嘌呤序列强烈且序列选择性地结合[Nielsen, P. E., Egholm, M., Berg, R. H. & Buchardt, O. (1991) Science 254, 1497 - 1500]。研究得出结论，与双链DNA的结合是通过链置换实现的，其中PNA与含腺嘌呤的沃森 - 克里克互补链结合，而含胸腺嘧啶的链则以几乎单链的构象被挤出。这个模型可能提供了一种通用的方法，通过沃森 - 克里克氢键碱基对识别来获得双链DNA中任何序列的序列特异性识别，因此，严格确定合成的DNA结合配体的这种结合模式至关重要。我们现在通过电子显微镜报告了这样的结果。此外，我们表明PNA与闭环DNA的结合导致双螺旋解旋，大约每10个碱基对解旋一圈双螺旋。在低盐浓度下形成的DNA - PNA复合物（在氯化钠浓度高于40 mM时，只有一小部分DNA分子显示复合物形成）具有异常高的动力学稳定性，即使将盐浓度提高到500 mM也不会解离。
It was recently found that polyamide nucleic acid (PNA) analogues consisting of thymines attached to an aminoethylglycine backbone bind strongly and sequence-selectively to adenine sequences of oligonucleotides and double-stranded DNA [Nielsen, P. E., Egholm, M., Berg, R. H. & Buchardt, O. (1991) Science 254, 1497-1500]. It was concluded that the binding to double-stranded DNA was accomplished via strand displacement, in which the PNA bound to the Watson-Crick complementary adenine-containing strand, whereas the thymine-containing strand was extruded in a virtually single-stranded conformation. This model may provide a general way in which to obtain sequence-specific recognition of any sequence in double-stranded DNA by Watson-Crick hydrogen-bonding base-pair recognition, and it is thus paramount to rigorously establish this binding mode for synthetic DNA-binding ligands. We now report such results from electron microscopy. Furthermore, we show that binding of PNA to closed circular DNA results in unwinding of the double helix corresponding to approximately one turn of the double helix per 10 base pairs. The DNA.PNA complex, which is formed at low salt concentration (only a small portion of DNA molecules show complex formation at NaCl concentration higher than 40 mM), is exceptionally kinetically stable and cannot be dissociated by increasing salt concentration up to 500 mM.