Histone Tail Interactions and Functions in Chromatin

摘要： 真核细胞核内的DNA与组蛋白和其他蛋白质组装， 形成一个复杂的、多方面的复合体，称为染色质。染色质不仅 用于包装基因组，但染色质结构的元素已密切 整合到基因控制机制中。核心组蛋白尾部结构域对于 染色质内多层结构的形成和大部分信号 细胞核内的转导最终指导这些蛋白质的翻译后修饰。 结构域，以促进核过程，如转录。在一些情况下， 进行这些修饰的酶中的突变已经与各种 包括癌症在内的人类疾病。然而， 尾部结构域限定染色质结构，并最终限定染色质的功能性。 基本的DNA -仍然知之甚少。中所述工作的主要目标 这一建议是为了阐明核心组蛋白尾的分子机制， 结构域决定了高级染色质结构的形成以及乙酰化 在这些结构域中的特定赖氨酸改变了尾部结构和相互作用， 基因表达。我们的目标是：1）表征短程和远程间- 模型核小体中H3和H4尾结构域的核小体相互作用， 核小体阵列，2）确定连接体组蛋白H1，结构蛋白H1。 转录因子HMGN或染色质重塑活性特异性改变 3）定量评估所选尾结构域的结合 结构域和乙酰化对这些相互作用的影响，在重建和天然 染色质我们将使用几种新的方法，包括定点化学 尾-DNA相互作用的映射、UV激光交联方法和其他化学方法 探测方法来研究尾部结构域的结构和相互作用。 此外，我们将使用化学保护方法和专门标记的核的NMR 组蛋白，以定量评估单个组蛋白的盐依赖性结合稳定性 核小体内的尾巴。这项工作将促进我们对关键分子的理解 影响基因表达控制的机制，并最终导致疾病， 癌症

Abstract: DNA within the eukaryotic cell nucleus is assembled with histones and other proteins to form a complicated, multifaceted complex known as chromatin. Chromatin not only serves to package the genome but elements of chromatin structure have been intimately integrated into gene control mechanisms. The core histone tail domains are essential for the formation of multiple levels of structure within chromatin and a large portion of signal transduction within the nucleus ultimately directs posttranslational modification of these domains in order to facilitate nuclear processes such as transcription. In several cases, mutations in enzymes that carry out these modifications have been linked to various diseases including cancers in humans. However, the molecular mechanisms by which the tail domains define chromatin structures - and ultimately the functionality of the underlying DNA - remain poorly understood. The primary goal of the work described in this proposal is to elucidate the molecular mechanisms by which the core histone tail domains dictate the formation of higher order chromatin structures and how acetylation of specific lysines within these domains alters tail structures and interactions to allow for gene expression. Our aims are to 1) characterize short-range and long-range inter- nucleosomal interactions of the H3 and H4 tail domains in model nucleosomes and nucleosome arrays, 2) Determine whether linker histone H1, the architectural transcription factor HMGN or a chromatin remodeling activity specifically alters interactions of the tail domains and to 3) quantitatively assess binding of selected tail domains and the effect of acetylation on these interactions in reconstituted and native chromatin. We will use several novel approaches including site-directed chemical mapping of tail-DNA interactions, a UV laser crosslinking approach, and other chemical probing approaches to investigate structures and interactions of the tail domains. Further, we will use a chemical protection approach and NMR of specifically labeled core histones to quantitatively assess the salt-dependent binding stability of individual histone tails within nucleosomes. This work will advance our understanding of critical molecular mechanisms that impinge upon control of gene expression and ultimately diseases such as cancer.