Selective nucleosome disruption by drugs that bind in the minor groove of DNA
Selective nucleosome disruption by drugs that bind in the minor groove of DNA
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DOI：
10.1074/jbc.274.38.27128
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发表时间：
1999-09-17
影响因子：
4.8
通讯作者：
Anderson, JN
中科院分区：
文献类型：
--
作者：
Fitzgerald, DJ;Anderson, JN
先前的研究表明，结合在DNA小沟中的药物会降低弯曲DNA的曲率。在这篇文章中，我们研究了这些药物对显示不同程度的内在曲率的DNA分子的核小体组装的影响，DAPI（4，6-diamidino-2-phenylindole）抑制组蛋白八聚体组装到来自秀丽隐杆线虫的192个碱基对的环状DNA片段上，并且使先前组装在该片段上的核小体不稳定。抑制作用是高度选择性的，因为它没有看到与nonbent分子，弯曲分子与非圆形形状，或总基因组DNA。这种显著的模板特异性归因于配体与分布在片段长度上的多个寡核苷酸A片段的结合。该效应的一种可能机制是结合的配体阻止DNA进一步压缩到小沟中，小沟是DNA组装成核小体所需的。为了进一步表征药物对染色质形成的影响，将核小体组装到322个碱基对的DNA片段上，该片段含有环状元件和侧翼的非弯曲DNA片段。然后使用各种核酸酶探针，包括核酸外切酶III、微球菌核酸酶、DNA酶I和限制性内切酶，确定核小体沿着片段的位置。这些研究的结果表明，在没有DAPI的情况下，核小体优先沿着圆形元件沿着定位，但在药物存在下，核小体组装到非弯曲的侧翼序列上。DAPI还诱导定向运动的核小体从环形元件上的nonbent侧翼序列时，核小体预组装到这个模板暴露于药物在生理相关条件下。
Previous studies have shown that drugs which bind in the DNA minor groove reduce the curvature of bent DNA. In this article, we examined the effects of these drugs on the nucleosome assembly of DNA molecules that display different degrees of intrinsic curvature, DAPI (4,6-diamidino-2-phenylindole) inhibited the assembly of a histone octamer onto a 192-base pair circular DNA fragment from Caenorhabditis elegans and destabilized a nucleosome that was previously assembled on this segment. The inhibitory effect was highly selective since it was not seen with nonbent molecules, bent molecules with noncircular shapes, or total genomic DNA. This marked template specificity was attributed to the binding of the ligand to multiple oligo A-tracts distributed over the length of the fragment, A likely mechanism for the effect is that the bound ligand prevents the further compression of the DNA into the minor groove which is required for assembly of DNA into nucleosomes. To further characterize the effects of the drug on chromatin formation, a nucleosome was assembled onto a 322-base pair DNA fragment that contained the circular element and a flanking nonbent segment of DNA. The position of the nucleosome along the fragment was then determined using a variety of nuclease probes including exonuclease III, micrococcal nuclease, DNase I, and restriction enzymes. The results of these studies revealed that the nucleosome was preferentially positioned along the circular element in the absence of DAPI but assembled onto the nonbent flanking sequence in the presence of the drug. DAPI also induced the directional movement of the nucleosome from the circular element onto the nonbent flanking sequence when a nucleosome preassembled onto this template was exposed to the drug under physiologically relevant conditions.