Mechanism and Function of HECT E3s in Ubiquitin and ISG15 Conjugation

HECT E3 在泛素和 ISG15 缀合中的机制和功能

• 批准号: 7623194
• 负责人: JON HUIBREGTSE
• 金额: $ 27.05万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-12-13 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7623194
• 关键词: 26S proteasome; Address; Angelman Syndrome; Binding; Biochemistry; Carcinogenesis Mechanism; Cells; Complex; Deubiquitinating Enzyme; Deubiquitination; Disease; Enzymes; Family; Funding Agency; Goals; Homologous Gene; Human; Human Papillomavirus; Immune response; In Vitro; Infection; Interferons; Intervention; Investigation; Link; Malignant Neoplasms; Malignant neoplasm of cervix uteri; Maps; Mediating; Membrane Protein Traffic; Molecular; Pathway interactions; Play; Polyubiquitin; Polyubiquitination; Post-Translational Protein Processing; Process; Protein Chemistry; Proteins; Regulation; Research Personnel; Retroviridae; Role; Route; Signal Pathway; Signal Transduction; Specificity; Surface; Syndrome; System; T-Lymphocyte; TGF Beta Signaling Pathway; UBA Domain; Ubiquitin; Ubiquitin Like Proteins; Ubiquitination; Viral; Virus; Work; Yeasts; base; enzyme mechanism; genetic regulatory protein; human disease; in vivo; microbial; notch protein; novel; preference; programs; public health relevance; response; ubiquitin ligase

DESCRIPTION (provided by applicant): Conjugation systems for ubiquitin and Ubiquitin-like proteins (Ubls) are generally organized into enzyme cascades involving E1, E2, and, E3 enzymes. Among the several classes of ubiquitin E3s, the HECT E3s are mechanistically unique in that they form a covalent enzyme-ubiquitin intermediate and participate directly in the chemistry of protein ubiquitination. HECT E3s play important roles in several disease states (cervical cancer, Angelman syndrome, Liddle's syndrome), disease-related pathways (TGF-beta signaling, Notch signaling, trafficking of membrane proteins), and are commandeered by several types of viruses (human papillomaviruses, EBV, retroviruses, Ebola). In addition, a single HECT E3, HercS, is critical for conjugation of ISG15, a type 1 interferon-induced Ubl that plays a role in the innate immune response to viral and microbial infections. These examples highlight the importance of understanding the mechanism, function, and regulation of HECT E3s. We have made important contributions toward understanding HECT E3 functions and mechanisms and propose to extend recent discoveries through three major lines of investigation. The first line of investigation, driven by our investigations on yeast Rsp5, will focus on the regulation of Rsp5 and its human homologs by physically associated deubiquitinating enzymes (DUBs). This represents a novel form of E3 regulation that may represent a point of intervention in altering HECT E3 function in human disease. The second line of investigation will address the mechanistic basis for the distinction between HECT E3s that catalyze K63-linked polyubiquitination and those that catalyze K48- linked polyubiquitination. This is an important problem because the ultimate consequences of these two types of ubiquitination are distinct. The third line of investigation will focus on the mechanism and regulation of ISG15 conjugation system by the HercS HECT E3. We will identify the complete set of factors required for HercS-dependent ISG15 conjugation and determine how this single E3 directs conjugation to perhaps hundreds of ISG15 target proteins. A thorough understanding of the biochemistry of ISG15 conjugation is essential for understanding the function of ISG15 in innate immune responses. Public health relevance: Protein modification by ubiquitin and Ubls serves to modify the stability, activity, or localization of many key cell regulatory proteins, and disruptions or alterations in these processes are seen in many disease states, particularly cancer. The elucidation of the biochemistry of the HECT family of ubiquitin ligases will impact our understanding of mechanisms of carcinogenesis, signaling pathways, and the response to viral and microbial infections.

描述（由申请人提供）：泛素和泛素样蛋白（UBL）的共轭系统通常组织成涉及E1，E2和E3酶的酶cascades。在几类泛素E3中，Hect E3在机械上是独一无二的，因为它们形成了共价酶 - 泛素蛋白中间体，并直接参与蛋白质泛素化的化学。 HECT E3在几种疾病状态（宫颈癌，Angelman综合征，Liddle's综合征），与疾病相关的途径（TGF-BETA信号传导，Notch信号，对膜蛋白的运输）中起重要作用，并由几种类型的病毒（人类乳头膜病毒，Ebv，Ebv，Retroviruses，reforviruses，ebola，ebola）命令。另外，单一HECT E3 HERCS对于ISG15的结合至关重要，ISG15是一种1型干扰素诱导的UBL，在对病毒和微生物感染的先天免疫反应中起作用。这些示例突出了理解hect E3S的机制，功能和调节的重要性。我们为理解E3功能和机制做出了重要的贡献，并建议通过三个主要的调查来扩展最新发现。在我们对酵母RSP5的调查的驱动的第一道研究中，将重点介绍通过物理相关的去泛素化酶（DUBS）的RSP5及其人类同源物的调节。这代表了E3调节的一种新型形式，它可能代表了改变人类疾病中E3功能的干预点。第二道调查将介绍催化K63连接多泛素化的E3的区别与催化K48连接的多泛素化的机械基础。这是一个重要的问题，因为这两种类型的泛素化的最终后果是不同的。第三条调查将重点关注HERCS HECT E3的ISG15共轭系统的机理和调节。我们将确定与HERC依赖性ISG15共轭所需的完整因素集，并确定该单个E3如何将共轭引导到数百种ISG15靶蛋白。对ISG15共轭的生物化学的透彻理解对于理解ISG15在先天免疫反应中的功能至关重要。公共卫生相关性：泛素和UBL的蛋白质修饰可修改许多关键细胞调节蛋白的稳定性，活性或定位，以及这些过程中的破坏或改变，在许多疾病状态下，尤其是癌症。泛素连接酶Hect家族的生物化学的阐明将影响我们对癌变机制，信号通路以及对病毒和微生物感染的反应的理解。