Structural and functional studies of ubiquitin kinases

活着的有机体及其组成细胞必须对环境线索做出反应，才能适应和生存。虽然大多数反应是通过基因调节蛋白质水平的缓慢变化，但快速变化可以通过对蛋白质进行化学修饰来实现，以调节它们在细胞中的作用。这些翻译后修饰(PTM)对地球上所有形式的生命都是必不可少的，并有不同的味道。其中最常见的两种是：1)由蛋白激酶进行的磷酸化，以及2)由泛素连接酶进行的泛素化。最近，我的实验室和其他人发现，泛素分子本身也会被磷酸化。这种修饰是由一种名为PINK1的激酶执行的，它参与了对神经元长期生存至关重要的质量控制途径。这种蛋白质几乎存在于所有动物身上，从昆虫到人类。磷酸化的泛素是细胞中激活Parkin的关键信号，Parkin是一种泛素连接酶，参与了许多细胞过程，包括蛋白质质量控制、神经元存活、对细菌病原体的抗性和糖/脂代谢。 我推测PINK1是使泛素磷酸化的蛋白激酶家族中的第一个成员。我的研究计划的长期目标是在分子结构水平上描述泛素激酶家族的特征。我的实验室使用了广泛的结构生物学方法，包括X射线结晶学，这使我们能够以非常高的清晰度确定酶的3D结构。我的第一个目标是确定PINK1如何识别泛素并在特定残基上添加磷酸。我的第二个目标是识别和研究其他泛素激酶，通过表征它们在哪里以及如何修改泛素。这些研究定义了我的研究计划，目的是了解连接酶和激酶等酶如何改变其他蛋白质，以及PTM如何调控细胞生存和功能。

Living organisms and their constituent cells must respond to environmental cues to adapt and survive. Whereas responses are mostly mediated by slow changes in protein levels through genes, rapid changes can be achieved by chemically modifying proteins in order to modulate their roles in the cell. These post-translational modifications (PTMs) are essential to all forms of life on Earth and come in different flavours. Two of the most common are: 1) phosphorylation, carried out by protein kinases, and 2) ubiquitination, carried out by ubiquitin ligases. Recently, my laboratory and others discovered that the molecule ubiquitin itself is subject to phosphorylation. The modification is carried out by a kinase named PINK1 that is involved in a quality control pathway essential for the long-term survival of neurons. This protein can be found in nearly all animals, from insects to humans. Phosphorylated ubiquitin is a key signal in cells for the activation of parkin, a ubiquitin ligase that is involved in a number of cellular processes including protein quality control, neuronal survival, resistance to bacterial pathogens, and sugar/lipid metabolism. I hypothesize that PINK1 is the first member of a family of kinases that phosphorylate ubiquitin. The long-term objective of my research program is to characterize the family of ubiquitin kinases at the molecular structure level. My laboratory uses a wide-range of structural biology methods including X-ray crystallography, which enables us to determine the 3D structure of enzymes with very high definition. My first aim is to determine how PINK1 recognizes ubiquitin and adds a phosphate on a specific residue. My second aim is to identify and study other ubiquitin kinases, by characterizing where and how they modify ubiquitin. These studies define my research program on understanding how enzymes like ligases and kinases alter other proteins, and how PTMs regulate cell survival and function.