Studies on a Widely Distributed Phage Tail-Derived Toxin Injection System

广泛分布的噬菌体尾源毒素注射系统的研究

• 批准号: RGPIN-2017-06858
• 负责人: Davidson, Alan
• 金额: $ 5.17万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=648717
• 关键词: Studies; Widely; Distributed; Phage; Tail

The viruses that infect bacteria (bacteriophages or phages) are the most abundant biological entities on earth. Most phages possess an icosahedral head containing their double-stranded DNA genome and a “tail” attached to one vertex of the head. The tail is responsible for attaching to the host bacterium and delivering the genome to the interior of the cell. As such, phage tails are very complex nanomachines with the ability to specifically bind the outer surface of bacteria, penetrate the cell wall and membranes, and inject macromolecules (DNA and proteins) into the cytoplasm. The tremendous effectiveness of phage tails as macromolecular injection devices has led to their being co-opted by bacteria for a variety of purposes, as exemplified by the Type VI secretion system, which is a widespread phage tail-derived virulence determinant in diverse Gram-negative organisms. ***The subject of this proposal is another contractile phage tail-derived injection system known as the Photorhabdus Virulence Cassette (PVC). Few PVCs have been characterized despite their sporadic occurrence in almost all bacterial clades and in Archaea. In addition to proteins similar to phage tail proteins, PVC operons also encode proteins commonly associated with secretion systems, such as a AAA ATPases and toxins. Two different PVCs have been shown to kill insect cells and another stimulates morphogenesis of a marine tube worm. The functions of many hundreds of other diverse PVCs are unknown. ***Most bacterial species within the Streptomyces genus encode PVCs, but no studies have ever been undertaken on them. We have found that the PVC operon is expressed in a cell cycle specific manner within one Streptomyces species and that the operon encodes a phage tail-like entity. We have identified distinct phenotypes in strains bearing mutations in PVC operons. Our future work is aimed at uncovering the functions of PVCs in Streptomyces, determining the biochemical properties and functions of individual PVC components, and gaining insight into the general roles in nature of these mysterious structures. ***Streptomyces produce a huge diversity of antibiotics and other useful pharmaceuticals. Our preliminary data indicate that PVCs play a role in Streptomyces antibiotic production, and further insight into this function may be significant to the antibiotic field. Additionally, PVCs represent a unique, soluble protein injecting nanomachine with the potential to inject proteins into a variety of eukaryotic cells. Determining how PVCs target cells would allow us to direct PVCs to any desired cell type. Similarly, deciphering the mechanism by which PVCs inject proteins presents the potential to inject any desired protein into a targeted cell. Thus, the knowledge gained through our work will create opportunities to engineer PVCs for a variety of novel biotechnological purposes that could be relevant in agriculture, industry, and human health.

感染细菌的病毒(噬菌体或噬菌体)是地球上最丰富的生物实体。大多数噬菌体都有一个二十面体的头部，其中包含它们的双链DNA基因组，还有一条“尾巴”附着在头部的一个顶点上。尾巴负责附着到宿主细菌上，并将基因组运送到细胞内部。因此，噬菌体尾巴是一种非常复杂的纳米机器，能够特异性地结合细菌的外表面，穿透细胞壁和细胞膜，并将大分子(DNA和蛋白质)注入细胞质。噬菌体尾巴作为大分子注射装置的巨大有效性导致它们被细菌用于各种目的，如VI型分泌系统，这是一种在各种革兰氏阴性生物中广泛存在的噬菌体尾巴衍生的毒力决定因素。*这项提案的主题是另一种可收缩的噬菌体尾部衍生注射系统，称为Photorhabdus毒力盒(PVC)。尽管在几乎所有的细菌分支和古生菌中都有零星出现，但很少有PVC的特征。除了与噬菌体尾部蛋白类似的蛋白质外，PVC操纵子还编码与分泌系统相关的蛋白质，如AAA-ATPase和毒素。两种不同的聚氯乙烯被证明可以杀死昆虫细胞，另一种可以刺激海洋管虫的形态发生。其他数百种不同的PVC的功能尚不清楚。*链霉菌属中的大多数细菌都编码PVCs，但还没有对它们进行过研究。我们已经发现，在一个链霉菌中，PVC操纵子以细胞周期特异性的方式表达，并且该操纵子编码一个类似噬菌体尾巴的实体。我们已经在携带聚氯乙烯操纵子突变的菌株中确定了不同的表型。我们未来的工作旨在揭示聚氯乙烯在链霉菌中的功能，确定单个聚氯乙烯组分的生化性质和功能，并深入了解这些神秘结构在自然界中的一般作用。*链霉菌产生种类繁多的抗生素和其他有用的药物。我们的初步数据表明，聚氯乙烯在链霉菌的抗生素生产中发挥了作用，进一步了解这一功能可能对抗生素领域具有重要意义。此外，PVCs代表了一种独特的、可溶的蛋白质注射纳米机器，有可能将蛋白质注射到各种真核细胞中。确定PVCs靶细胞的方式将允许我们将PVCs定向到任何所需的细胞类型。同样，破译PVCs注射蛋白质的机制可能会将任何所需的蛋白质注射到靶细胞中。因此，通过我们的工作获得的知识将创造机会，为各种可能与农业、工业和人类健康相关的新型生物技术目的设计聚氯乙烯。