Mechanisms of ubiquitin signaling in chromatin-mediated processes

项目总结 包装DNA的组蛋白的翻译后修饰在调节 DNA损伤的转录和修复。这项研究计划的目标是确定分子 小分子泛素与组蛋白结合的机制 通过包括甲基化和乙酰化在内的修饰来调节基因表达并维持 基因组完整性。由于组蛋白泛素化和甲基化的错误调节 癌症，这些研究的结果可以用来设计针对分子的新药 参与这些通路的机器。这项研究计划的一个主要焦点将是机制。 通过组蛋白H2B的单一泛素化触发激活基因所需的一系列事件 转录，包括组蛋白H3的甲基化和辅助RNA的组蛋白伴侣的招募 通过染色质模板转录DNA的聚合酶。结合了X射线结晶学， 低温电子显微镜和核磁共振、单分子生物物理、溶液生物化学和细胞基础 将使用方法来研究如SAGA之类的辅助激活复合体是如何结合它们的染色质的 底物结合组蛋白去泛素化、乙酰化和组蛋白甲基化识别 启动转录。我们还将研究过氧化氢泛素化引发组蛋白的机制 甲基化并确定不同脱泛素酶介导的不同机制 核小体动力学。在这个程序中要解决的泛素信号的另一个方面是 连接到DNA烷基化位点的泛素链损伤修复酶的机制。 拟议的研究将产生的分子洞察力将为开发 针对目前还没有有效治疗方法的癌症的新的化疗方法。

PROJECT SUMMARY Post-translational modifications of the histone proteins that package DNA play a central role in regulating transcription and repair of DNA damage. The goal of this research program is to determine the molecular mechanism by which attachment of the small protein, ubiquitin, to histone proteins functions in concert with modifications including methylation and acetylation to regulate gene expression and maintain genome integrity. Since misregulation of histone ubiquitination and methylation characterizes many cancers, the results of these studies can be used to design new drugs that target the molecular machines involved in these pathways. A major focus of this research program will be on the mechanism by which monoubiquitination of histone H2B triggers a cascade of events needed to activate gene transcription, including methylation of histone H3 and recruitment of histone chaperones that assist RNA polymerase in transcribing DNA through a chromatin template. A combination of x-ray crystallography, cryo-electron microscopy and NMR, single molecule biophysics, solution biochemistry and cell-based approaches will be used to study how coactivator complexes such as SAGA bind their chromatin substrates and combine histone deubiquitination, acetylation and recognition of histone methylation to activate transcription. We will also study the mechanism by which H2B ubiquitination triggers histone methylation and determine the distinct mechanism by which different deubiquitinating enzymes mediate nucleosome dynamics. Another aspect of ubiquitin signaling to be addressed in this program is the mechanism by which ubiquitin chains attached to sites of DNA alkylation damage recruit repair enzymes. The molecular insights that will result from the proposed studies will provide a foundation for developing new chemotherapies that target cancers for which there currently are no effective treatments.