The type III secretion system 'translocation-stop' activity of EspZ

EspZ的III型分泌系统“易位停止”活性

• 批准号: BB/J015245/1
• 负责人: Gad Frankel
• 金额: $ 50.59万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FJ015245%2F1
• 关键词: type; III; secretion; system; translocation

Escherichia coli is a bacterium that often inhabits the intestines of warm-blooded animals. Subsets of E. coli have evolved the ability to cause disease. One such group are enterohaemorrhagic E. coli (EHEC), which can cause bloody diarrhoea in humans. Infections can involve life-threatening complications affecting the kidneys and are frequently acquired via the food chain and farm environment from ruminants. Cattle are a major reservoir of EHEC, including the O157:H7 form that has caused serious outbreaks in recent years. Enteropathogenic E. coli (EPEC) are a related subset of bacteria that cause acute watery diarrhoea in infants in the developing world. Both types of E. coli rely on a 'molecular syringe' to colonise the intestines and produce disease. This syringe, encoded by a cluster of genes called the locus of enterocyte effacement (LEE), serves to inject a set of bacterial proteins termed effectors into cells lining the intestines. This process, known as Type III secretion, enables the bacteria to take control of processes inside host cells for their own benefit. Our research has shown that Type III secretion is vital for adherence of EHEC and EPEC to the gut lining and to interfere with the induction of host responses that might otherwise resolve the infection. To orchestrate host cell pathways, the bacteria must deliver Type III secreted effectors in the required order and amounts. Moreover, it is necessary to control the timing of delivery, and the duration of action and location of effectors inside host cells. Our recent research has indicated that the effector protein EspZ plays an important role in controlling the flow of effector proteins into host cells. It appears to do this only once injected, and host cells that have been engineered to express EspZ are resistant to injection of effectors. Bacteria that lack EspZ cause excessive damage to host cells, likely because they inject effectors at elevated levels. These data suggest that EspZ is a novel natural inhibitor of Type III secretion that may arrest the injection process once it has been delivered into host cells. Our pilot data suggest that EspZ may interact with other LEE-encoded proteins to close the pore created by the syringe, and that it may be modified once it enters host cells. The nature and consequences of interactions between EspZ and other proteins, and of modification of EspZ, are not known. We therefore propose to:1. Define when EspZ is injected into host cells, and whether targeting of the protein to the host cell membrane coincides with arrest of Type III secretion.2. Identify proteins that interact with EspZ and determine how such interactions arrest Type III secretion.3. Define the nature and consequences of modification of EspZ inside host cells.4. Determine the role of EspZ in bacterial persistence and disease in animal models.An understanding of how EspZ modulates Type III secretion will aid the rational design of strategies to control EHEC and EPEC infections and carriage by farm animals. Inhibitors of the process may be used to treat infections in humans or reservoir hosts. Moreover, we will explore the possibility of creating transgenic animals that are refractory to infection as a consequence of expression of EspZ in intestinal cells.

大肠杆菌是一种经常居住在温血动物的肠道的细菌。大肠杆菌的子集已经发展出引起疾病的能力。这样的群体是肠内大肠杆菌（EHEC），可能会导致人类血腥的腹泻。感染可能涉及影响肾脏的生命并发症，并经常通过反刍动物的食物链和农场环境获取。牛是EHEC的主要水库，包括近年来导致严重爆发的O157：H7形式。肠病大肠杆菌（EPEC）是一个相关的细菌子集，在发展中国家的婴儿中引起急性水性腹泻。两种类型的大肠杆菌都依靠“分子注射器”来定植肠子并产生疾病。该注射器由称为肠肠细胞effacement（Lee）的一组基因编码，用于将一组称为效应子的细菌蛋白注入肠道内的细胞中。这个被称为III型分泌的过程使细菌能够控制宿主细胞内部的过程，以便自身。我们的研究表明，III型分泌对于EHEC和EPEC遵守肠道衬里至关重要，并干扰可能解决感染的宿主反应的诱导。为了策划宿主细胞通路，细菌必须按照所需的顺序和量提供III型分泌效应子。此外，有必要控制递送时间，以及宿主细胞内效应子的作用持续时间和位置。我们最近的研究表明，效应蛋白ESPZ在控制效应蛋白流入宿主细胞中起着重要作用。它似乎只有一次注射一次，并且已经设计以表达ESPZ的宿主细胞对效应子的注射有抵抗力。缺乏ESPZ的细菌会对宿主细胞造成过多的损害，这可能是因为它们以升高水平注入效应子。这些数据表明，ESPZ是一种新型的自然抑制剂III型分泌物，一旦将注射过程递送到宿主细胞中。我们的试点数据表明，ESPZ可能与其他Lee编码的蛋白质相互作用，以关闭注射器产生的孔，并且一旦进入宿主细胞，就可以对其进行修改。 ESPZ与其他蛋白质之间的相互作用的性质和后果以及ESPZ的修饰的性质和后果尚不清楚。因此，我们建议：1。定义何时将ESPZ注射到宿主细胞中，以及将蛋白质靶向宿主细胞膜是否与III型分泌的停滞相吻合2。确定与ESPZ相互作用的蛋白质并确定这种相互作用如何阻止III型分泌3。定义ESPZ内部细胞内ESPZ修饰的性质和后果。4。确定ESPZ在细菌持久性和疾病中的作用在动物模型中。了解ESPZ如何调节III型分泌将有助于控制EHEC和EPEC感染以及农场动物运输的策略。该过程的抑制剂可用于治疗人类或储层宿主中的感染。此外，我们将探索创建因肠细胞中ESPZ表达而产生的转基因动物的可能性。

项目成果

The Citrobacter rodentium type III secretion system effector EspO affects mucosal damage repair and antimicrobial responses.

• DOI: 10.1371/journal.ppat.1007406
• 发表时间: 2018-10
• 期刊: PLoS pathogens
• 影响因子: 6.7
• 作者: Berger CN;Crepin VF;Roumeliotis TI;Wright JC;Serafini N;Pevsner-Fischer M;Yu L;Elinav E;Di Santo JP;Choudhary JS;Frankel G
• 通讯作者: Frankel G