Helical structure determines different susceptibilities of dsDNA, dsRNA, and tsDNA to counterion-induced condensation.
Helical structure determines different susceptibilities of dsDNA, dsRNA, and tsDNA to counterion-induced condensation.
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DOI：
10.1016/j.bpj.2013.03.033
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发表时间：
2013-05
影响因子：
3.4
通讯作者：
A. Kornyshev;S. Leikin
中科院分区：
文献类型：
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作者：
A. Kornyshev;S. Leikin
最近关于反离子诱导的核酸螺旋凝聚成聚集体的研究产生了几个令人费解的观察结果。例如，三价钴六价离子凝聚了双链(Ds)DNA低聚物，而不是它们更高电荷的dsRNA对应物。二价碱土金属离子可凝聚三链(Ts)DNA低聚物，但不能凝聚dsDNA。在这里，我们表明，这些违反直觉的实验结果可以在具有螺旋电荷模体的分子之间相互作用的静电拉链模型中得到合理解释。我们报告了统计力学计算，揭示了螺旋结构和热涨落对寡聚核酸之间的静电相互作用的影响。结合对低聚和更长螺旋的预测，我们还解释了最近关于反离子电荷、结构和化学作用的实验研究。我们认为，静电拉链引力可能是核酸凝聚的主要甚至主导力量。
Recent studies of counterion-induced condensation of nucleic acid helices into aggregates produced several puzzling observations. For instance, trivalent cobalt hexamine ions condensed double-stranded (ds) DNA oligomers but not their more highly charged dsRNA counterparts. Divalent alkaline earth metal ions condensed triple-stranded (ts) DNA oligomers but not dsDNA. Here we show that these counterintuitive experimental results can be rationalized within the electrostatic zipper model of interactions between molecules with helical charge motifs. We report statistical mechanical calculations that reveal dramatic and nontrivial interplay between the effects of helical structure and thermal fluctuations on electrostatic interaction between oligomeric nucleic acids. Combining predictions for oligomeric and much longer helices, we also interpret recent experimental studies of the role of counterion charge, structure, and chemistry. We argue that an electrostatic zipper attraction might be a major or even dominant force in nucleic acid condensation.