TRIM proteins and the SUMO pathway: a systematic and functional analysis

TRIM蛋白是一个蛋白质大家族，它们具有共同的基本结构，但在功能和亚细胞定位上却非常不同。它们含有一个被称为无名指的区域，该区域具有“E3泛素连接酶”活性，这意味着它指导着被称为泛素化的蛋白质修饰过程。泛素化是一种小蛋白质泛素与其他蛋白质的连接。人们认为它们的泛素连接酶活性是TRIM蛋白功能的中心。一些TRIM蛋白被发现自身受到另一种被称为SUMO化的蛋白质修饰过程的影响。相扑也包括一种小蛋白，相扑，连接到另一种蛋白质，并发生在共识的位置。苏莫化通常调节修饰蛋白在细胞内的定位、稳定性和/或功能。有趣的是，泛素化和糖基化是相互依赖的过程。我们实验室的工作表明，有一种人类TRIM5，尤其是TRIM5，含有一个共同的SUMO化位点，调节相邻环域的泛素连接酶活性。计算机搜索SUMO化共识位点表明，大多数人TRIM蛋白都含有这样的基序，这意味着SUMO化在该家族蛋白质的功能中起着重要和普遍的作用。我们建议建立一个长期目标是破译TRIM蛋白和SUMO化之间的功能关系的研究计划。我们将克隆、表达和纯化所有~80个人TRIM蛋白，包括一些从未研究过的蛋白。他们结合相扑和被SUMOyl化的能力将被调查。SUMO化将在细胞中进行测试，并使用体外测试，并将确定SUMO化位点。通过分析它们对亚细胞定位、稳定性和E3泛素连接酶活性的影响，将评估SUMO化和相扑相关基序在TRIM蛋白行为中的作用。这项研究计划将首次详细描述TRIM蛋白的SUMO化情况，并将揭示SUMO化在TRIM功能中的作用。我们的系统方法将使我们能够发现多个TRIM蛋白共同的调控途径，并表征TRIM家族中研究较少的成员。除了显著提高科学知识，这项研究计划在蛋白质工程中也有潜在的应用。

TRIM proteins are a large family of proteins that share a common basic structure but are very diverse in their functions and subcellular localization. They harbor a domain called the RING finger which has an “E3 ubiquitin ligase” activity, meaning that it guides the protein modification process known as ubiquitination. Ubiquitination consists in the linkage of a small protein, ubiquitin, to other proteins. It is believed that their ubiquitin ligase activity is central to the function of TRIM proteins. Some TRIM proteins were found to be themselves subjected to another protein modification process known as SUMOylation. SUMOylation also consists in the linkage of a small protein, SUMO, to another protein and occurs at consensus sites. SUMOylation often modulates the intracellular localization, stability and/or function of the modified proteins. Interestingly, ubiquitination and SUMOylation are inter-dependent processes. Work in our laboratory showed that one human TRIM in particular, TRIM5, harbors a consensus SUMOylation site that modulates the ubiquitin ligase activity of the adjacent RING domain. Computer searches for SUMOylation consensus sites suggested that the majority of human TRIM proteins harbor such motifs, implying that SUMOylation plays an important and general role in the function of proteins of this family. We propose to establish a research program with the long-term goal of deciphering the functional relationships between TRIM proteins and SUMOylation. We will clone, express and purify all ~80 human TRIM proteins, including some that have never been studied. Their capacity to bind SUMO and to be SUMOylated will be investigated. SUMOylation will be tested in cells and using in vitro assays, and SUMOylation sites will be identified. The role of SUMOylation and SUMO-relevant motifs in the behavior of TRIM proteins will be assessed by analyzing their impact on the subcellular localization, stability and E3 ubiquitin ligase activity. This research program will yield the first detailed description of the TRIM proteins SUMOylation landscape and will uncover the role of SUMOylation in TRIM functions. Our systematic approach will allow us to uncover regulatory pathways common to multiple TRIM proteins and to characterize poorly studied members of the TRIM family. In addition to significantly advancing scientific knowledge, this research program has potential applications in protein engineering.