Molecular Mechanisms of Histone Acetyltransferases

组蛋白乙酰转移酶的分子机制

• 批准号: 7088738
• 负责人: JOHN M DENU
• 金额: $ 23.8万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7088738
• 关键词: 3T3 cells; acetylation; acyltransferase; biological signal transduction; chemical binding; chemical kinetics; crystallization; enzyme activity; enzyme mechanism; enzyme structure; enzyme substrate complex; high performance liquid chromatography; mitogen activated protein kinase; molecular shape; nucleosomes; phosphorylation

DESCRIPTION (provided by applicant): Reversible post-translation modification of proteins is a major mechanism of transmitting cellular signals and regulating protein function. Protein phosphorylation is a common modification that can act as a "switch" of protein function in response to extracellular signals. Most extracellular signals are propagated by a diverse class of protein kinases called MAP (Mitogen activated protein) kinases, which themselves are tightly regulated by phosphorylation. These phosphorylation cascades signal to chromatin to bring about appropriate gene expression. Recent findings now indicate that specific chromatin modifications (primarily on histone proteins) are critical in regulating expression of target genes induced by these pathways. The most studied histone modification is acetylation of lysine side-chains within the amino terminal tails. Also, phosphorylation, methylation and ubiquitinylation of histones are believed to integrate (synergistically or antagonistically) with acetylation to generate a "histone code" necessary for the proper levels of gene expression from altered chromatin structure. Misregulation of components of these pathways results in a variety of diseases, the most prevalent being cancer. In the previous grant period, we determined the molecular mechanisms of protein phosphatases that down-regulate the MAP kinases. In the next grant period we have shifted our focus to investigate the ultimate target of MAP kinase signaling, chromatin modification. It is unclear how chromatin modifying enzymes carry out their function on nucleosomes. The proposed work will investigate the molecular mechanism of nucleosomal acetylation by histone acetyltransferase (HAT) complexes. Here, we will focus on the basic mechanism of the MYST family of HATs (Aim 1), and investigate how HAT enzymes recognize, acetylate and propagate acetylation on nucleosomal arrays (Aim 2). An enzyme-based "histone code" hypothesis will be investigated using semi-synthetic nucleosomal arrays containing site-specific modifications on histone H3 (Aim 3).

描述（由申请人提供）：可逆的蛋白质翻译后修饰是传递细胞信号和调节蛋白质功能的主要机制。蛋白质磷酸化是一种常见的修饰，可以作为响应细胞外信号的蛋白质功能的“转换”。大多数细胞外信号被称为MAP（有丝分裂原活化蛋白）激酶的多种蛋白激酶传播，该激酶本身受磷酸化的严格调节。这些磷酸化级联对染色质信号引起了适当的基因表达。最近的发现现在表明，特定的染色质修饰（主要是在组蛋白上）对于调节这些途径诱导的靶基因的表达至关重要。研究最多的组蛋白修饰是氨基末端尾巴内赖氨酸侧链的乙酰化。同样，据信组蛋白的磷酸化，甲基化和泛素化也可以与乙酰化相结合（协同或拮抗），从而产生从染色质结构改变的基因表达水平的“组蛋白代码”所必需的“组蛋白代码”。这些途径组成部分的不正调导致多种疾病，最普遍的是癌症。在上一个赠款期间，我们确定了下调MAP激酶的蛋白质磷酸酶的分子机制。在下一个赠款期间，我们将重点转移到了MAP激酶信号传导，染色质修饰的最终目标。目前尚不清楚染色质修饰酶如何在核小体上发挥作用。提出的工作将研究组蛋白乙酰转移酶（HAT）复合物的核小体乙酰化的分子机制。在这里，我们将重点关注Myst Hats家族的基本机制（AIM 1），并研究HAT酶在核小体阵列上如何识别，乙酰化和传播乙酰化（AIM 2）。将使用含有组蛋白H3的位点特异性修饰的半合成核小体阵列研究基于酶的“组蛋白代码”假设（AIM 3）。