Novel anti-bacterial toxins: mode of action and delivery between cells

新型抗菌毒素：作用方式和细胞间传递

• 批准号: 2255681
• 金额: --
• 依托单位: University of Dundee
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2255681
• 关键词: Novel; anti; bacterial; toxins; mode

Many bacterial pathogens use the Type VI secretion system (T6SS) nanomachine to fire toxic 'effector' proteins directly into target cells. It is becoming increasingly apparent that the T6SS plays a key role in the virulence and competitiveness of diverse Gram-negative bacteria, including important human pathogens. Pathogens can use T6SSs to directly target eukaryotic organisms, as classical virulence factors. Alternatively, many pathogens can use T6SSs to target other bacterial cells, killing or inhibiting rivals. 'Anti-bacterial' T6SSs thus provide a competitive mechanism to allow pathogens to proliferate in polymicrobial infection sites or environmental reservoirs and ultimately cause disease. Anti-bacterial T6SSs inject toxic proteins into target bacterial cells, efficiently killing them or inhibiting their growth. Recent work in the field, including from our lab, suggests that different T6SSs secrete multiple, diverse and novel anti-bacterial toxins. Whilst several broad classes have been functionally characterised to date, particularly enzymic toxins attacking the bacterial cell wall, nucleic acid or cell membrane, many other toxins appear unrelated to known proteins. It is important to discover the vulnerable cellular targets of such toxins since they may reveal new targets for antibiotic or other drug design; the toxins may also represent valuable research tools to understand basic bacterial physiology.In the SJC lab, we have identified new T6SS-secreted anti-bacterial toxins which do not fall into the previously described classes. Therefore their mode of action and cellular target in susceptible cells is unknown. The focus of this PhD project will be to study one (or more) of these new toxins in order to determine: (1) its mode of toxicity and cellular target in susceptible cells; (2) its pathway of secretion and any cellular functions of the target cell which are required in order for the toxin to exert its effect; (3) how self-resistance or 'immunity' to the toxin in the secreting cell is achieved; and (4) distribution of related toxins in different organisms. In order to tackle part (1) and inform on the remaining parts, the molecular bacteriology expertise of the SJC lab will be complemented by the target discovery expertise of the SW lab, who utilise state-of-the-art chemical biology and other approaches to determine the mode of action of new anti-parasite and anti-microbial compounds.This project will provide research training in a broad-spectrum of molecular microbiological techniques, including: molecular biology and genetic analyses; protein purification and biochemical assays; microscopy and other cell biological approaches. The student will further utilise state-of-the-art chemical biology strategies, including thermal shift proteomics - an unbiased, label-free method to search for the targets of drugs or in this instance T6SS-secreted anti-bacterial toxins. Advanced transcriptomics and genomics approaches are also available in the host or collaborating labs, as required. The student will have many opportunities to present their work at internal and external meetings and to interact with other research groups.

许多细菌病原体使用VI型分泌系统（T6SS）纳米机器将有毒的“效应”蛋白直接发射到靶细胞中。越来越明显的是，T6SS在多种革兰氏阴性细菌（包括重要的人类病原体）的毒力和竞争力中起着关键作用。病原体可以利用t6ss直接靶向真核生物，作为经典的毒力因子。另外，许多病原体可以使用t6ss靶向其他细菌细胞，杀死或抑制竞争对手。因此，“抗菌”t6ss提供了一种竞争机制，允许病原体在多微生物感染部位或环境库中增殖，并最终导致疾病。抗菌t6ss将有毒蛋白质注入目标细菌细胞，有效地杀死它们或抑制它们的生长。最近在该领域的工作，包括我们实验室的工作，表明不同的t6ss分泌多种多样的新型抗菌毒素。虽然到目前为止，已有几大类毒素在功能上得到了鉴定，尤其是攻击细菌细胞壁、核酸或细胞膜的酶毒素，但许多其他毒素似乎与已知蛋白质无关。重要的是发现这些毒素的脆弱细胞靶点，因为它们可能揭示抗生素或其他药物设计的新靶点；毒素也可能是了解基本细菌生理学的有价值的研究工具。在SJC实验室，我们发现了新的t6ss分泌的抗菌毒素，这些毒素不属于先前描述的类别。因此，它们在易感细胞中的作用方式和靶细胞是未知的。本博士项目的重点将是研究这些新毒素中的一种（或多种），以确定：(1)其毒性模式和易感细胞中的细胞靶点；（二）毒素的分泌途径和为使毒素发挥作用所必需的任何细胞功能；(3)如何在分泌细胞中实现对毒素的自我抵抗或“免疫”；(4)相关毒素在不同生物体中的分布。为了解决第(1)部分，并为其余部分提供信息，SJC实验室的分子细菌学专业知识将与SW实验室的目标发现专业知识相辅相成，后者利用最先进的化学生物学和其他方法来确定新的抗寄生虫和抗微生物化合物的作用模式。该项目将提供广谱分子微生物技术方面的研究培训，包括：分子生物学和遗传分析；蛋白质纯化和生化分析；显微镜和其他细胞生物学方法。该学生将进一步利用最先进的化学生物学策略，包括热移蛋白质组学——一种无偏见、无标签的方法，用于寻找药物靶点或在这种情况下，t6ss分泌的抗菌毒素。根据需要，宿主或合作实验室也可使用先进的转录组学和基因组学方法。学生将有很多机会在内部和外部会议上展示他们的工作，并与其他研究小组互动。