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将DNA包装成 染色质。具有组蛋白修饰活性的辅活化子复合体通过以下方式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。尽管在分子方面已经取得了重大进展 了解涉及真核转录的许多关键大分子机器，进展 由于这些大型复合体的结构信息有限，对共激活蛋白功能的理解一直比较滞后 以及它们与染色质的相互作用。这个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。一个主要的关注点是 关于组蛋白泛素化在转录调控中的作用，以及组蛋白泛素化与组蛋白泛素化之间的相互作用 组蛋白泛素化、甲基化和乙酰化。我们方法中的两个主要工具是低温电子 显微镜(冷冻-EM)和大量设计染色质模板的开发，这些模板已经 有助于我们捕获与修饰的染色质模板结合的多亚单位复合体。自.以来 从这个奖项开始，我们在酶的结构和生化研究方面取得了实质性的进展 介导组蛋白H_2B泛素化和组蛋白H_3甲基化之间的串扰的复合体 确定了SAGA复合体的组蛋白H2B脱泛素化模块的新抑制剂。我们正在进行的研究 正在解决控制泛素结合酶对组蛋白H2B-K120的专一性的机制， 这个泛素标记在调节染色质的获取中的作用，以及组蛋白密码在 调节组蛋白甲基转移酶和去甲基酶。我们研究的许多络合物，包括MLL-1， DOT1L复合体和USP22/SAGA Dub模块在多种癌症中发挥核心作用。我们的 因此，机理研究和药物发现努力为开发新型药物提供了基础 以这些染色质修饰酶为靶点的治疗。

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.