Guanine tetraplex formation by short DNA fragments containing runs of guanine and cytosine
Guanine tetraplex formation by short DNA fragments containing runs of guanine and cytosine
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DOI：
10.1016/s0006-3495(97)78235-3
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发表时间：
1997-10-01
影响因子：
3.4
通讯作者：
Vorlickova, M
中科院分区：
文献类型：
--
作者：
Penazova, H;Vorlickova, M
使用CD光谱法，用短DNA片段研究了鸟嘌呤四链体的形成，其中将胞嘧啶残基系统地添加到鸟嘌呤的5'或3'末端。钾离子诱导的G-四链体更容易与片段具有鸟嘌呤运行在5'端，这是正好相反的趋势，报告的（G+T）寡核苷酸。然而，本（G+C）片段同时采用其他构象复杂的分析。我们证明，在低离子强度下进行的反复冻融是一种合适的方法，专门稳定（G+C）DNA片段中的四链体。与KCl相比，重复的冻融循环更好地稳定了具有在3'端上运行的鸟嘌呤的片段的四链体。鸟嘌呤阻断产生四链体的趋势使d（G（5））·d（C-5）双链体不稳定，其链解离，产生稳定的（dG（5））和单链（dC（5））四链体。与d（G（5）C（5））和d（G（5）C（5））相反，即使是自身互补的d（C（3）G（3））或d（C（5）G（5）），重复冻融也诱导四链体;因此，后一种寡核苷酸优选四链体而不是明显非常稳定的双链体。四链体仅包括鸟嘌呤嵌段，而5'端胞嘧啶既不干扰四链体的形成也不干扰四链体结构。
Using CD spectroscopy, guanine tetraplex formation was studied with short DNA fragments in which cytosine residues were systematically added to runs of guanine either at the 5' or 3' ends. Potassium cations induced the G-tetraplex more easily with fragments having the guanine run at the 5' end, which is just an opposite tendency to what was reported for (G+T) oligonucleotides. However, the present (G+C) fragments simultaneously adopted other conformers that complicated the analysis. We demonstrate that repeated freezing/thawing, performed at low ionic strength, is a suitable method to exclusively stabilize the tetraplex in the (G+C) DNA fragments. In contrast to KCI, the repeated freeze/thaw cycles better stabilized the tetraplex with fragments having the guanine run on the 3' end. The tendency of guanine blocks to generate the tetraplex destabilized the d(G(5)).d(C-5) duplex whose strands dissociated, giving rise to a stable tetraplex of (dG(5)) and single-stranded (dC(5)). in contrast to d(G(5)C(5)) and d(G(5)C(5)), repeated freezing/thawing induced the tetraplex even with the self-complementary d(C(3)G(3)) or d(C(5)G(5)); hence the latter oligonucleotides preferred the tetraplex to the apparently very stable duplex. The tetraplexes only included guanine blocks while the 5' end cytosines interfered neither with the tetraplex formation nor the tetraplex structure.