Micromechanical Study of Hyperacetylated Nucleosomes Using Single Molecule Transverse Magnetic Tweezers.
Micromechanical Study of Hyperacetylated Nucleosomes Using Single Molecule Transverse Magnetic Tweezers.
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DOI：
10.3390/ijms24076188
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发表时间：
2023-03-24
影响因子：
5.6
通讯作者：
Sarkar, Abhijit
中科院分区：
文献类型：
--
作者：
Gaire, Santosh;Fabian Jr, Roberto L. L.;Adhikari, Raghabendra;Tuma, Pamela L.;Pegg, Ian L.;Sarkar, Abhijit
关键词：
核小体是DNA和组蛋白的稳定复合物，对基因组的正常功能至关重要。这些结构必须在基因表达、复制和修复等过程中被解开和拆卸。组蛋白翻译后修饰（PTMs）在调节核小体的结构变化中起着重要作用。然而，这些修饰作用的潜在机制尚不清楚。在这项研究中，我们报告了使用横向磁镊子对高乙酰化组蛋白组成的dna -蛋白质复合物进行单分子微操作的实验结果。在将高乙酰化组蛋白引入样品室之前，以小于4的力预延伸λ-DNA进行实验。当组蛋白与DNA形成复合物时，DNA缩短，核小体阵列暴露在不断增加的张力下，导致DNA延伸的量子化变化，步长为（整数倍）~50。我们还比较了PTM组蛋白和天然组蛋白的实验结果，并收集了两种组蛋白在相同的力范围（2-80）和加载率下的数据。我们的数据显示，高乙酰化核小体需要约2.5的解结合力，这与天然组蛋白所需的解结合力相似。此外，我们发现了天然组蛋白和高乙酰化组蛋白的步长分布之间的明显差异，并发现与用天然组蛋白重建的系链相比，用高乙酰化组蛋白压实的系链中的大多数核小体在明显低于6的力下进行了解体。
Nucleosomes are stable complexes of DNA and histone proteins that are essential for the proper functioning of the genome. These structures must be unwrapped and disassembled for processes such as gene expression, replication, and repair. Histone post-translational modifications (PTMs) are known to play a significant role in regulating the structural changes of nucleosomes. However, the underlying mechanisms by which these modifications function remain unclear. In this study, we report the results of single molecule micromanipulation experiments on DNA–protein complexes composed of hyperacetylated histone proteins using transverse magnetic tweezers. The experiments were conducted by pre-extending λ-DNA with a force less than 4 before introducing hyperacetylated histones into the sample chamber. The DNA shortened as the histones formed complexes with it and the nucleosome arrays were then exposed to increasing tension, resulting in quantized changes in the DNA’s extension with step sizes of (integral multiples of) ~50 . We also compared results of experiments using PTM histones and native histones with data collected for both types of histones for the same force ranges (2–80 ) and loading rates. Our data show that hyperacetylated nucleosomes require an unbinding force of around ~2.5 , which is similar to that required for native histones. Moreover, we identified clear differences between the step-size distributions of native and hyperacetylated histones and found that in contrast to tethers reconstituted with native histones, the majority of nucleosomes in tethers compacted with hyperacetylated histones underwent disassembly at forces significantly lower than 6 .
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DOI：
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发表时间：
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影响因子：
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作者：
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通讯作者：
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DOI：
10.1093/pnasnexus/pgac312
发表时间：
2023-02
期刊：
PNAS NEXUS
影响因子：
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作者：
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通讯作者：
Ferreira, Patricia