Structural and Functional Analysis of the Chd1 Chromatin Remodeler

摘要 染色质重构体是依赖于ATP的DNA转位酶，它催化分解、重组和 核小体在整个真核基因组中的重新定位。从多种类型的癌症和 与重塑分子失活相关的发育障碍，染色质重塑对正常至关重要 成长和发展。重塑需要组蛋白-DNA相互作用的短暂和可控的破坏， 不同的重建器家族拥有独特的域，被认为有助于或规范 保守的ATPase马达。我们的Chd1染色质重构体的晶体结构提供了第一个观点 ATPase马达的调节，显示了ATPase马达的DNA结合表面是如何被 色域。从ISWI重建器家族的工作中可以看出，Chd1的自我抑制性质 染色域已被证明是调节核小体上的ATPase作用的一种常见策略。 然而，目前还不清楚这种域-域交互如何使重构器能够感知和响应 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 核小体上Chd1结构的发现，其中Chd1 DNA结合域被发现 通过核小体的回旋直接与染色质ATPase通信。我们建议测试一下 Chd1结构域间相互作用负责感知核小体外DNA的假说 这些领域共同努力，实现特定的重塑结果。 除了重构体调节外，染色质重构体重新定位核小体的机制 人们对DNA的了解也很少。用ISWI重建器进行有趣的单分子FRET实验 揭示了阶梯式和不连续的运动，这表明DNA的行为就像 核小体。我们将测试这一想法，并进一步研究高进程步骤所需的DNA相互作用 我们也对Chd1进行了观察。总而言之，这些研究将提供新的机械洞察力，了解 染色质重构体操纵核小体的结构，并使用域-域通信来 规范改造者的行为。 好了！

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. !