Cell：染色质重构调节子在核小体中的特异性和方向性

<p style="text-align: left;" align="center"><img src="http://www.bioon.com/biology/UploadFiles/201206/2012062418584818.jpg" alt="" width="375" height="375" border="0" />
6月22日，<em>Cell</em>杂志报道了染色质重构调节子在核小体中特异性和方向性的最新研究成果。</p>
<p style="text-align: left;" align="center"><!--more--></p>
众多染色质重构调节子是如何相互合作，在基因的开始和结束位点处组织核小体的还不清楚。研究者发现在酿酒酵母细胞全基因组范围内，SWI/ SNF，RSC，ISW1a，ISW1b，ISW2，INO80等染色质重构调节子复合体与单个核小体相结合，并通过缺失分析证实，这些复合体通过辅助核小体定位行使其功能。

研究者采用超高分辨率ChIP-exo（一种基于染色质免疫沉淀的基因组作图方法，用于确定目标蛋白质结合到基因组的位置）研究Isw2基因，以在基因组范围内确定其组织模式和在核小体内的定位方向。

研究发现，染色质重构调节子在基因的起始和结束位置与特定核小体位点相互作用，并在移动中的核小体内，基因的5'和3'末端产生朝向或背向无核小体基因组区域的定向性。根据其生化和晶体结构信息建立的模型，研究者将isw2的连接子结合区域定位于基因启动子内部，与Reb1因子结合的位点紧靠。 
<div id="ztload">
<div>
<div>

<img src="http://www.bioon.com/biology/UploadFiles/201206/2012062418544625.jpg" alt="" width="113" height="149" border="0" hspace="0" />

<a title="" href="http://dx.doi.org/10.1016/j.cell.2011.10.017" target="_blank">doi:</a><a title="" href="http://www.cell.com/abstract/S0092-8674(12)00592-2" target="_blank">10.1016/j.cell.2011.10.017</a>
PMC:
PMID:

</div>
<div>

<br/><strong>Genome-wide Nucleosome Specificity and Directionality of Chromatin Remodelers</strong><br/>


Kuangyu Yen, Vinesh Vinayachandran, Kiran Batta, R. Thomas Koerber, B. Franklin Pugh

How chromatin remodelers cooperate to organize nucleosomes around the start and end of genes is not known. We determined the genome-wide binding of remodeler complexes SWI/SNF, RSC, ISW1a, ISW1b, ISW2, and INO80 to individual nucleosomes in Saccharomyces, and determined their functional contributions to nucleosome positioning through deletion analysis. We applied ultra-high-resolution ChIP-exo mapping to Isw2 to determine its subnucleosomal orientation and organization on a genomic scale. Remodelers interacted with selected nucleosome positions relative to the start and end of genes and produced net directionality in moving nucleosomes either away or toward nucleosome-free regions at the 5 and 3 ends of genes. Isw2 possessed a subnucleosomal organization in accord with biochemical and crystallographic-based models that place its linker binding region within promoters and abutted against Reb1-bound locations. Together, these findings reveal a coordinated position-specific approach taken by remodelers to organize genic nucleosomes into arrays.

<br/>来源：生物谷

</div>
</div>
</div>