Regulation of Ubiquitin Chain Topology

说明（申请人提供）泛素（Ub）是调节蛋白质降解、定位和其他活性的重要信号分子。 通常，Ub分子的C-末端通过E1/E2/E3反应级联与蛋白质底物的赖氨酸残基共价缀合，并且该修饰通过去泛素化酶（DUB）的作用而逆转。PolyUb链可以通过第一个Ub分子的赖氨酸基团和下一个Ub分子的C-末端之间的连接进一步组装在基底上。我们目前的蛋白质组学分析显示，Ub分子上的所有七个赖氨酸基团都可以用于形成polyUb链，包括Lys 6，Lys 11，Lys 27，Lys 29，Lys 33，Lys 48和Lys 63。我们认为功能不同的polyUb链的形成是泛素化和去泛素化的调节步骤。为了研究这些polyUb连接的功能，我们将首先开发一种质谱技术来量化所有七个polyUb连接的丰度，然后研究DUBs和polyUb链拓扑结构之间的催化特异性。 此外，我们将专注于定义Lys 11 polyUb链的功能。我们的研究将导致polyUb链拓扑结构的通用蛋白质组学工具的发展，以及对polyUb链的多样性和功能的更好理解。

DESCRIPTION (PROVIDED BY APPLICANT) Ubiquitin (Ub) is an essential signal molecule regulating protein degradation, localization and other activities. Generally the C-terminus of the Ub molecule is covalently conjugated to lysine residues of protein substrates by the E1/E2/E3 reaction cascade, and the modification is reversed by the action of deubiquitinating enzymes (DUBs). PolyUb chains can be further assembled on the substrates by the linkage between lysine groups of the first Ub molecule and the C-terminus of the next. Our current proteomic analysis revealed that all seven lysine groups on the Ub molecule can be utilized for the formation of polyUb chains, including Lys6, Lys11, Lys27, Lys29, Lys33, Lys48, and Lys63. We propose that the formation of functionally distinct polyUb chains is a regulatory step for ubiquitination and deubiquitination. To examine the function of these polyUb linkages, we will first develop a mass spectrometry technology for quantifying the abundance of all seven polyUb linkages, and then study the catalytic specificity between DUBs and polyUb chain topology. Moreover, we will focus on defining the function of Lys11 polyUb chains. Our studies will lead to the development of general proteomic tools for polyUb chain topology and better understanding of the diversity and function of polyUb chains.