Dissecting regulatory mechanisms governing histone H3 lysine 9 methylation

真核生物的基因组被组蛋白覆盖，组蛋白作为信号平台，形成基因组调控和保护的组成部分。这些信号是组蛋白尾部的翻译后修饰，其中有“写入器”和“擦除器”酶以及特异性结合标记的阅读器蛋白。该项目的重点是一个酶家族称为SUV 39，这是在组成异染色质系统的核心。我们研究了来自人类和裂殖酵母的蛋白质，这是一个非常有用的模型系统，用于了解染色质信号传导的基本机制。SUV 39蛋白存款组蛋白H3赖氨酸9甲基标记（H3 K9me），这是建立沉默的表观遗传状态，可以从一代传播到下一代，而不会改变潜在的DNA序列。在哺乳动物中，SUV 39酶已被证明是健康发育所必需的，它们的失调与各种癌症有关。我们和其他实验室的最近工作表明，特定的翻译后修饰，特别是在接近H3K9的残基上的泛素化，赖氨酸14，可以刺激裂殖酵母SUV 39蛋白Clr 4对H3K9的活性超过250倍。我们有进一步的证据，Clr 4本身的磷酸化调节其H3K9甲基转移酶活性。该提案是一项合作努力，利用我们在X射线晶体学和NMR的高分辨率结构方法方面的专业知识，可视化并了解这些翻译后修饰如何控制SUV 39蛋白。我们将通过NMR进一步确定Clr 4活性调节中各种结构状态的作用。对SUV 39蛋白的丰富了解将有助于推动癌症治疗方法的开发。

The genomes of eukaryotic organisms are covered by histone proteins, which act as a signalling platform that forms an integral part of the regulation and protection of the genome. The signals are post-translational modifications on histone tails for which there are "writer" and "eraser" enzymes as well as reader proteins that specifically bind the mark. This project focuses on an enzyme family called SUV39, which is at the heart of constitutive heterochromatin systems. We study proteins from human and fission yeast, a very informative model system for understanding the fundamental mechanisms of signalling on chromatin. SUV39 proteins deposit the histone H3 lysine 9 methyl marks (H3K9me), which are required to establish silent epigenetic states that can be propagated from one generation to the next without changes in the underlying DNA sequence. In mammals, SUV39 enzymes have been shown to be required for healthy development and their deregulation is associated with various cancers.Recent work in our and other laboratories has revealed that specific post-translational modifications, in particular ubiquitination on a residue close to H3K9, lysine 14, can stimulate the activity of the fission yeast SUV39 protein Clr4 on H3K9 by more than 250-fold. We have furthermore evidence, that phosphorylation on Clr4 itself regulates its H3K9 methyltransferase activity. This proposal is a collaborative effort that leverages our expertise in the high-resolution structural approaches of X-ray crystallography and NMR to visualize and understand how these post-translational modifications control SUV39 proteins. We will further determine by NMR the role of various structural states in the regulation of Clr4's activity. This rich understanding of SUV39 proteins will be beneficial to driving efforts forward to develop therapeutic approaches in cancer.