Mechanisms of ubiquitin signaling in chromatin-mediated processes Diversity Supplement

项目摘要 真核基因被激活的机制与DNA包装成 染色质具有组蛋白修饰活性的辅激活因子复合物在这一过程中发挥重要作用， 改变染色质动力学和相互作用。尽管在分子生物学领域已经取得了重大进展， 了解真核转录中涉及的许多关键大分子机器， 由于这些大复合物的结构信息有限，对辅激活剂功能的理解已经滞后 以及它们与染色质的相互作用。该项目的重点是了解真核生物的调控， 转录以及组蛋白修饰和基因激活之间的联系。一个主要的重点是 关于组蛋白泛素化在调节转录中的作用，以及组蛋白泛素化与转录之间的相互作用机制， 组蛋白泛素化、甲基化和乙酰化。我们的方法中的两个主要工具是低温电子 显微镜（cryo-EM）和大量设计染色质模板的开发，这些模板已经被 有助于我们捕获与修饰的染色质模板结合的多亚基复合物。以来 从这个奖项开始，我们在酶的结构和生物化学研究方面取得了实质性进展 复合物介导组蛋白H2 B泛素化和组蛋白H3甲基化之间的串扰， 鉴定了佐贺复合物的组蛋白H2 B去泛素化模块的新型抑制剂。我们正在进行的研究 正在解决泛素结合酶对组蛋白H2 B-K120的特异性的控制机制， 这种泛素标记在调节进入染色质中的作用，以及组蛋白编码串扰在 调节组蛋白甲基转移酶和脱甲基酶。我们研究的许多复合物，包括MLL-1， Dot 1 L复合物和USP 22/佐贺DUB模块在多种癌症中发挥核心作用。我们 因此，机制研究和药物发现努力为开发新的药物提供了基础。 靶向这些染色质修饰酶的治疗剂。

PROJECT ABSTRACT The mechanism by which eukaryotic genes are activated is inextricably linked with the packaging of DNA into chromatin. Coactivator complexes with histone-modifying activities play essential roles in this process by altering chromatin dynamics and interactions. Although there have been major advances in a molecular understanding many of the key macromolecular machines involved in eukaryotic transcription, progress in understanding coactivator function has lagged due to limited structural information on these large complexes and their interactions with chromatin. This project has focused on understanding the regulation of eukaryotic transcription and the connection between histone modifications and gene activation. A major focus has been on the role of histone ubiquitination in regulating transcription, and on the mechanism of cross-talk between histone ubiquitination, methylation and acetylation. Two major tools in our approach are cryo-electron microscopy (cryo-EM) and the development of a large array of designer chromatin templates, which have been instrumental in our ability to capture multisubunit complexes bound to modified chromatin templates. Since the start of this award we have made substantial progress in our structural and biochemical studies of enzyme complexes that mediate cross-talk between histone H2B ubiquitination and histone H3 methylation and have identified novel inhibitors of the SAGA complex’s histone H2B deubiquitinating module. Our ongoing studies are addressing the mechanism governing specificity of ubiquitin conjugating enzymes for histone H2B-K120, the role of this ubiquitin mark in regulating access to chromatin, and role of histone code cross-talk in regulating histone methyltransferases and demethylases. Many of the complexes we study, including MLL-1, Dot1L complexes, and the USP22/SAGA DUB module play a central role in a variety of cancers. Our mechanistic studies and drug discovery efforts are thus providing a foundation for developing novel therapeutics that target these chromatin-modifying enzymes.