为什么Na+在拥挤的环境中比K+更倾向于凝结DNA?
Egor S Kolesnikov1,2, Ivan Yu Gushchin1, Petr A Zhilyaev3
1Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia.
The Journal of chemical physics
|October 10, 2023
概括
根据分子动力学模拟,离子比离子在拥挤的溶液中更好地压缩DNA. 这一发现解释了实验观察,并预测了依赖序列的DNA凝结.
科学领域:
- 生物物理学的生物物理.
- 计算生物学 计算生物学
- 分子动力学分子动力学
背景情况:
- 像 (Na+) 和 (K+) 这样的单价酸在DNA凝结中起着至关重要的作用.
- 聚乙烯糖醇 (PEG) 等拥挤剂会影响溶液中的DNA的行为.
- 实验研究表明,Na+在PEG的存在下比K+更有效地促进DNA紧缩.
研究的目的:
- 在拥挤的条件下为Na+和K+的差异DNA凝聚提供分子层次的解释.
- 用计算方法研究离子结合和相互作用在DNA聚合中的作用.
- 为了做出关于DNA序列效应和挤压剂对凝结物的相互作用的预测.
主要方法:
- 用分子动力学 (MD) 模拟来建模各种单价和PEG.的溶液中的短DNA复合体.
- "离子结合模型"被用来分析离子-DNA相互作用和DNA-DNA聚合.
- 进行了自由能量计算,以量化DNA聚合的能量有利性.
主要成果:
- 在PEG的存在下,MD模拟显示了相邻DNA复合体周围的K+离子相比,外结合的Na+离子数量更高.
- 在NaCl溶液中,DNA聚合的自由能量被发现比KCl溶液更有利 (每基对至少0.2kBT).
- 在Na+存在时,DNA复合体之间的自由能量吸引被预测是依赖序列的,有利于富含AT的序列.
结论:
- 在拥挤的条件下Na+离子的结合增加为其优越的DNA紧缩能力提供了定性解释,与K+相比.
- DNA序列组成影响了Na+介导的DNA-DNA吸引力的强度,富含AT的复合体更容易凝结.
- 高亲和度拥挤剂可以,反直觉地,削弱离子介导的DNA吸引力,可能阻碍凝结.
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