Structural and Functional Analysis of the Chd1 Chromatin Remodeler

摘要 染色质重塑蛋白是ATP依赖性DNA移位酶，其催化分解、重组和降解。 核小体在真核基因组中的重新定位。从多种类型的癌症和 与重塑失活相关的发育障碍，染色质重塑是正常发育所必需的。 增长和发展。重塑需要短暂且受控地破坏组蛋白-DNA相互作用， 不同家族的重塑者拥有独特的结构域，被认为有助于或调节 保守的ATP酶马达。我们的Chd 1染色质重塑物的晶体结构提供了 ATP酶马达调节，显示ATP酶马达的DNA结合表面如何被邻近的 染色体结构域。从ISWI重塑家族的工作中可以看出，Chd 1的自抑制性质 染色体结构域已被证明是调节核小体上ATP酶作用的常见策略。 然而，目前尚不清楚这种域-域相互作用如何使重塑者能够感知和响应 特定的核小体底物，或实现独特的重塑结果。在这里，我们跟进我们最近的 发现Chd 1在核小体上的结构，发现Chd 1 DNA结合结构域 穿过核小体的回纹直接与染色质-ATP酶通讯。我们建议测试 假设Chd 1的结构域间相互作用负责感测核小体外的DNA 并且这些区域共同工作以实现特定的重塑结果。 除了重塑调节，染色质重塑重新定位核小体的机制 对沿着DNA也知之甚少。有趣的单分子FRET实验与ISWI重塑 已经揭示了DNA的阶梯状和不连续运动，这表明DNA的行为就像弹簧一样。 核小体我们将测试这一想法，并进一步研究DNA相互作用所需的高加工步骤 我们也观察到了Chd 1。总之，这些研究将提供新的机制见解， 染色质重塑者操纵核小体的结构，并使用结构域-结构域通信， 调节重塑作用。 !

ABSTRACT Chromatin remodelers are ATP-dependent DNA translocases that catalyze disassembly, reassembly, and repositioning of nucleosomes throughout eukaryotic genomes. As evidenced from multiple types of cancer and developmental disorders associated with remodeler inactivation, chromatin remodeling is essential for normal growth and development. Remodeling requires transient and controlled disruption of histone-DNA interactions, with different families of remodelers possessing unique domains thought to assist or regulate action of a conserved ATPase motor. Our crystal structure of the Chd1 chromatin remodeler provided the first view of ATPase motor regulation, showing how a DNA-binding surface of the ATPase motor was blocked by adjacent chromodomains. As seen from work with the ISWI remodeler family, the auto-inhibitory nature of the Chd1 chromodomains has proven to be a common strategy for regulating ATPase action on the nucleosome. However, it remains unclear how such domain-domain interactions enable remodelers to sense and respond to particular nucleosome substrates, or achieve unique remodeling outcomes. Here we follow up our recent discoveries of Chd1 architecture on the nucleosome, where the Chd1 DNA-binding domain was found to directly communicate with the chromo-ATPase across the gyres of the nucleosome. We propose to test the hypothesis that inter-domain interactions of Chd1 are responsible for sensing DNA outside the nucleosome and that domains work together to achieve particular remodeling outcomes. In addition to remodeler regulation, the mechanism by which chromatin remodelers reposition nucleosomes along DNA is also poorly understood. Intriguing single molecule FRET experiments with the ISWI remodeler have revealed step-like and discontinuous movements DNA, suggesting that DNA behaves as a spring on the nucleosome. We will test this idea and further investigate DNA interactions needed for high processive steps that we also observe for Chd1. Together, these studies will provide new mechanistic insights into how chromatin remodelers manipulate the structure of the nucleosome and use domain-domain communication to regulate remodeler action. !