Molecular basis of transcription factor regulation by ubiquitin specific proteases

泛素信号几乎控制所有的细胞功能，包括转录。在这个项目中，我们将研究泛素化，特别是去泛素化如何通过修饰转录因子来控制基因表达的分子基础。在人类基因组中编码的最大的去泛素化酶家族是泛素特异性蛋白酶（USP）。我们将研究最近发现的单泛素化事件对转录因子ELK-1的结构和相互作用的影响。在有丝分裂原的反应中，ELK-1促进细胞生长、分化和存活。有趣的是，ELK-1的活性被其DNA结合ETS结构域的单泛素化抑制。反过来，ELK-1泛素化可以通过去泛素化酶USP 17逆转，以调节细胞周期进程和增殖，但目前没有关于USP 17的结构信息，并且如何实现特异性尚不清楚。我们将使用结构生物学工具来研究单泛素化对ELK-1构象的影响，并使用生物化学和生物物理方法来探测其与DNA的相互作用。在第二个调查线，我们将表征ELK-1与去泛素化酶USP 17和其他USP的相互作用，以更好地了解ELK-1的泛素化调控机制，以及USP如何特异性识别泛素化底物蛋白。总之，这将揭示转录因子的泛素化影响其结构和相互作用的机制，以及它如何通过去泛素化酶的作用来逆转以控制基因表达。

The ubiquitin signal virtually controls all cellular functions including transcription. In this project we will study the molecular basis of how ubiquitination and particularly deubiquitination control gene expression by modifying a transcription factor. The largest family of deubiquitinating enzymes encoded in the human genome are ubiquitin specific proteases (USPs). We will investigate the impact of recently discovered mono-ubiquitination events on the structure and interactions of transcription factor ELK-1. In response to mitogens ELK-1 promotes cell growth, differentiation, and survival. Interestingly, ELK-1's activity is inhibited by mono-ubiquitination of its DNA binding ETS domain. In turn, ELK-1 ubiquitination can be reversed by the deubiquitinating enzyme USP17 to regulate cell cycle progression and proliferation, but no structural information is currently available for USP17 and how specificity is achieved is unknown. We will use structural biology tools to investigate the effect of mono-ubiquitination on the conformation of ELK-1 and probe its interaction with DNA using biochemical and biophysical methods. In a second line of investigation we will characterize the interaction of ELK-1 with the deubiquitinating enzyme USP17 and other USPs in order to better understand the mechanism of ELK-1's regulation by ubiquitination and how USPs specifically recognize ubiquitinated substrate proteins. Together, this will shed light onto the mechanism by which ubiquitination of a transcription factor influences its structure and interactions and how it can be reversed by the action of deubiquitinating enzymes to control gene expression.