Exploring the Strategies of Bacterial Subversion of the Host Ubiquitin System: The Mechanism of Novel E3 Ligases (NEL) from Shigella

探索细菌颠覆宿主泛素系统的策略：志贺氏菌新型 E3 连接酶 (NEL) 的机制

• 批准号: BB/R003750/1
• 负责人: Benjamin Stieglitz
• 金额: $ 42.39万
• 依托单位: Queen Mary University of London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FR003750%2F1
• 关键词: Exploring; Strategies; Bacterial; Subversion; Host

The aim of this project is to elucidate the mechanism by which bacterial ubiquitin ligases undermine the innate immune response of an infected cell. Our understanding will help to uncover new therapeutic strategies to fight the emerging threat of antimicrobial resistance. The innate immune response is the first line of defence against bacterial infections. It involves activation of a variety of cellular reactions, which cause inflammation of the infected tissue. The activation steps of the inflammatory response depend to a great extent on the ubiquitylation machinery of the cell. The ubiquitylation machinery consists of a cascade of different enzymes, which act in sequence to modify target proteins with ubiquitin chains. Ubiquitin chains consist of the small protein ubiquitin. The attachment of ubiquitin chains is tightly regulated and catalysed by a class of enzymes known as E3 ubiquitin ligases. Many pathogenic bacteria deploy a set of E3 ubiquitin ligases which they introduce into the cytosol of the infected host cell. These bacterial ubiquitin ligases, known as NELs (Novel E3 Ligase), are capable to modify components of the host ubiquitylation machinery with ubiquitin. The activity of the bacterial NELs interferes with normal function of the host ubiquitylation machinery which ultimately subverts the innate immune response in favour of the invading pathogen. It is currently unknown how NELs highjack the host ubiquitylation machinery to modify their target proteins. The human pathogen Shigella flexneri are highly infectious bacteria which are responsible for a severe form of dysentery known as shigellosis. Shigellosis a significant cause of morbidity and mortality worldwide. Some NELs from Shigella are targeting the linear ubiquitin chain assembly complex LUBAC which results in functional interference of the complex. LUBAC is a key component of the ubiquitylation machinery and required for the activation of the inflammatory response upon bacterial infection. We will use a combination of structural and biophysical techniques to determine the molecular mechanism by which the NEL IpaH1.4 from Shigella modifies LUBAC with ubiquitin and uncover how this modification inhibits LUBAC activity. Our findings will shed light on the molecular mechanism of Shigella pathogenesis and may provide new routes to restrict bacterial infections.

这个项目的目的是阐明细菌泛素连接酶破坏受感染细胞的先天免疫反应的机制。我们的理解将有助于发现新的治疗策略，以对抗新出现的抗菌素耐药性威胁。先天免疫反应是抵御细菌感染的第一道防线。它涉及各种细胞反应的激活，这些反应会导致感染组织的炎症。炎症反应的激活步骤在很大程度上依赖于细胞的泛素化机制。泛素化机制由一系列不同的酶组成，这些酶依次作用于用泛素链修饰目标蛋白。泛素链由小蛋白泛素组成。泛素链的连接受到一类被称为E3泛素连接酶的酶的严格调控和催化。许多致病细菌部署一组E3泛素连接酶，它们被引入受感染宿主细胞的胞浆中。这些细菌泛素连接酶被称为NEL(新型E3连接酶)，能够用泛素修饰宿主泛素化机制的组成部分。细菌NEL的活性干扰了宿主泛素化机制的正常功能，最终破坏了有利于入侵病原体的先天免疫反应。目前还不清楚NELs是如何劫持宿主泛素化机制来修改它们的目标蛋白的。人类病原体福氏志贺氏菌是一种高度传染性的细菌，它导致了一种被称为志贺氏菌病的严重痢疾。志贺氏菌病是全世界发病率和死亡率的重要原因。志贺氏菌的一些NEL靶向于线性泛素链组装复合体LUBAC，导致该复合体的功能干扰。LUBAC是泛素化机制的关键组成部分，是细菌感染时激活炎症反应所必需的。我们将使用结构和生物物理技术相结合的方法来确定志贺氏菌的Nel IpaH1.4用泛素修饰LUBAC的分子机制，并揭示这种修饰是如何抑制LUBAC活性的。我们的发现将有助于阐明志贺氏菌致病的分子机制，并可能为限制细菌感染提供新的途径。

项目成果

Auxiliary-assisted chemical ubiquitylation of NEMO and linear extension by HOIP

NEMO 的辅助化学泛素化和 HOIP 的线性延伸

• DOI: 10.25418/crick.11636844
• 发表时间: 2020
• 作者: Burlina F