Structural and functional studies of ubiquitin kinases

生物体及其组成细胞必须对环境信号作出反应，以适应和生存。虽然反应主要是通过基因介导的蛋白质水平的缓慢变化，但快速变化可以通过化学修饰蛋白质来实现，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，并且有不同的风味。其中最常见的两种是：1）磷酸化，由蛋白激酶进行，和2）泛素化，由泛素连接酶进行。最近，我的实验室和其他人发现，分子泛素本身是受磷酸化。这种修饰是由一种名为PINK 1的激酶进行的，该激酶参与了神经元长期存活所必需的质量控制途径。这种蛋白质可以在几乎所有动物中找到，从昆虫到人类。磷酸化泛素是细胞中激活帕金蛋白的关键信号，帕金蛋白是一种泛素连接酶，参与许多细胞过程，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/脂质代谢。 我假设PINK 1是磷酸化泛素的激酶家族的第一个成员。我的研究计划的长期目标是在分子结构水平上表征泛素激酶家族。我的实验室使用了广泛的结构生物学方法，包括X射线晶体学，这使我们能够以非常高的分辨率确定酶的3D结构。我的第一个目标是确定PINK 1如何识别泛素并在特定残基上添加磷酸盐。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饰泛素。这些研究定义了我的研究计划，了解酶如连接酶和激酶如何改变其他蛋白质，以及PTM如何调节细胞存活和功能。

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.