Mechanisms of ubiquitin signaling in chromatin-mediated processes

项目摘要 包装DNA的组蛋白的翻译后修饰在调节DNA的表达中起着重要作用。 转录和修复DNA损伤。这项研究计划的目标是确定分子 小蛋白泛素与组蛋白的结合机制 通过包括甲基化和乙酰化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失调， 癌症，这些研究的结果可用于设计靶向分子的新药。 参与这些途径的机器。这项研究计划的一个主要重点将是机制 组蛋白H2B的单泛素化引发了激活基因所需的级联反应， 转录，包括组蛋白H3的甲基化和组蛋白伴侣的募集， 在通过染色质模板转录DNA中，聚合酶起作用。结合X射线晶体学， 冷冻电子显微镜和核磁共振，单分子生物物理学，溶液生物化学和细胞基础 方法将被用来研究辅激活复合物，如佐贺如何结合他们的染色质 底物和联合收割机结合组蛋白去泛素化、乙酰化和组蛋白甲基化的识别， 激活转录。我们还将研究H2B泛素化触发组蛋白的机制。 甲基化，并确定不同的去泛素化酶介导的不同机制 核小体动力学泛素信号的另一个方面要解决的这个程序是 连接到DNA烷基化损伤位点的泛素链募集修复酶的机制。 从拟议的研究中获得的分子见解将为开发 针对目前没有有效治疗方法的癌症的新化疗。

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.