DNA Wrapping and Distortion by an Oligomeric Homeodomain Protein
DNA Wrapping and Distortion by an Oligomeric Homeodomain Protein
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DOI：
10.1016/j.jmb.2008.08.004
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发表时间：
2008-10-31
影响因子：
5.6
通讯作者：
Gaston, Kevin
中科院分区：
文献类型：
--
作者：
Williams, Hannah;Jayaraman, Padma-Sheela;Gaston, Kevin
许多转录因子改变DNA或染色质结构。染色质结构的变化通常是由染色质结合蛋白、染色质修饰蛋白或其他转录辅激活蛋白或辅阻遏蛋白的募集引起的。然而，一些转录因子形成寡聚体组装，其本身可能诱导DNA构象和染色质结构的变化。富含脯氨酸的同源结构域（PRH/Hex）蛋白是调节细胞分化和细胞增殖的转录因子，并且在胚胎发育中具有多种作用。早些时候，我们发现PRH可以通过多种机制抑制转录，包括招募属于染色质结合蛋白TLE家族的辅阻遏蛋白。我们的体内交联研究表明，PRH在细胞中形成低聚复合物，各种生物物理技术表明，蛋白质形成八聚体。然而，到目前为止，我们对PRH寡聚化在调节启动子活性或直接由PRH在细胞中调节的启动子结构中所起的作用知之甚少。在这里，我们比较结合PRH和分离的PRH同源域的DNA片段与单个和多个PRH网站，使用凝胶阻滞试验和DNase I和化学足迹。我们表明，PRH寡聚体结合到多个网站内的人Goosecoid启动子具有高亲和力，PRH的结合带来DNA畸变。我们认为，PRH八聚体包裹DNA，以带来转录抑制。(C)2008爱思唯尔有限公司保留所有权利。
Many transcription factors alter DNA or chromatin structure. Changes in chromatin structure are often brought about by the recruitment of chromatin-binding proteins, chromatin-modifying proteins, or other transcription co-activator or co-repressor proteins. However, some transcription factors form oligomeric assemblies that may themselves induce changes in DNA conformation and chromatin structure. The proline-rich homeodomain (PRH/Hex) protein is a transcription factor that regulates cell differentiation and cell proliferation, and has multiple roles in embryonic development. Earlier, we showed that PRH can repress transcription by multiple mechanisms, including the recruitment of co-repressor proteins belonging to the TLE family of chromatin-binding proteins. Our in vivo crosslinking studies have shown that PRH forms oligomeric complexes in cells and a variety of biophysical techniques suggest that the protein forms octamers. However, as yet we have little knowledge of the role played by PRH oligomerisation in the regulation of promoter activity or of the architecture of promoters that are regulated directly by PRH in cells. Here, we compare the binding of PRH and the isolated PRH homeodomain to DNA fragments with single and multiple PRH sites, using gel retardation assays and DNase I and chemical footprinting. We show that the PRH oligomer binds to multiple sites within the human Goosecoid promoter with high affinity and that the binding of PRH brings about DNA distortion. We suggest that PRH octamers wrap DNA in order to bring about transcriptional repression. (C) 2008 Elsevier Ltd. All rights reserved.