盐离子、聚乙二醇与力对双根 DNA 扭转的影响
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国家自然科学基金项目(11772133)


Effects of Salt Ions, Polyethylene Glycol and Force on Twisted Structure of Double DNAs
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    摘要:

    目的 研究不同盐离子浓度、聚乙二醇浓度和力对双根 DNA 扭转超螺旋结构的影响。 方法 以 10 kb DNA为研究对象,利用磁镊的流动腔实验探究不同浓度盐离子(Na+、K+、Mg2+)、聚乙二醇( polyethylene glycol, PEG)和不同大小的力对双根 DNA 扭转编织体长度随圈数变化的影响。 结果 双根 DNA 扭转结构对盐离子浓度敏感,对PEG 不敏感。 离子浓度越大,编织体长度随圈数变化越平缓,且 Mg2+的静电屏蔽饱和浓度远低于单价阳离子。 拥挤环境对 DNA 的影响主要为轮廓长度压缩。 在 4 pN 以上力作用下 DNA 扭转结构更为稳定,2 pN 以下超螺旋结构波动较大。 结论 DNA 的编织体结构与力学性质受所处溶液离子浓度和力的影响。 研究结果有助于进一步探究染色质扭转受溶液环境影响的机制,并为拓扑异构酶在不同溶液条件下的作用效果提供参考。

    Abstract:

    Objective To investigate the effects of different salt ion concentration, polyethylene glycol (PEG) and force on structure of double DNAs braids. Methods Taking the 10 kb DNA as the research object, the effects of different concentrations of salt ions(Na+, K+, Mg2+), PEG and different forces on variation of relative extension of twisted double DNAs with rotation turns were investigated by flow chamber experiment of magnetic tweezers. Results The structure of double DNAs braids was sensitive to salt ion concentration but insensitive to PEG. With the increase of ion concentration, the extension of braids changed more gently with the rotation turns, and the electrostatic shielding saturation concentration of Mg 2+ was much lower than that of the monovalent cation. The effect of crowded environment on DNA was mainly the compression of contour length. The twisted structure of DNA was more stable under high force (above 4 pN), and fluctuated greatly under low force (lower than 2 pN). Conclusions The braiding structure and mechanical properties of DNA are affected by ion concentration in the solution and forces. The results may help to elucidate the mechanism of chromatin torsional torque affected by solution environment, and provide references for the function of topoisomerase under different solution conditions.

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周雨乐,高媛媛,肖波涛.盐离子、聚乙二醇与力对双根 DNA 扭转的影响[J].医用生物力学,2023,38(2):242-247

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  • 收稿日期:2022-06-30
  • 最后修改日期:2022-08-31
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  • 在线发布日期: 2023-04-25
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