CDI System-mediated Intra- and Inter-species Interactions in Burkholderia

描述（由申请方提供）：革兰氏阴性细菌类鼻疽伯克霍尔德氏菌是一种土壤腐养菌，是一种新出现的传染病病原体。它是类鼻疽的病原体，可导致急性肺部疾病、败血症，如果不及时治疗可能致命。虽然在东南亚和澳大利亚北方自然发现，但由于其潜在的武器化，它受到全球关注。细菌通常生活在多微生物群落中，因此已经进化出与邻居交流、合作和竞争的机制。一种这样的机制是接触依赖性生长抑制（CDI）系统。该系统由双伴侣分泌蛋白组成，并被细菌用来杀死邻近细胞并潜在地控制周围的种群。该系统的主要组成部分是一个大的表面外蛋白，BcpA，它含有一个有毒的C-末端（CT）。CT被递送到靶细菌细胞以诱导死亡，除非靶细胞含有免疫蛋白以阻断毒性活性。CDI系统的一个标志性特征是 CT和它们的同源免疫蛋白之间的多态性，以等位基因特异性方式保护。我们实验室的研究表明，非病原体B. Thailandensis用于细菌间竞争和生物膜形成。在这个建议中，我们将解决几个问题，伯克霍尔德氏菌型CDI系统。首先，我们将评估B的能力。假鼻疽利用其CDI系统进行细菌间杀灭。然后，当细菌与密切相关的生物接触时，W将建立CDI系统在种间杀伤中的作用。为了实现这一点，我们将评估B之间的种间竞争。类鼻疽和B.泰国茶此外，通过使用BcpA嵌合蛋白的研究，我们将分析BcpA的区域，这些区域可能在系统的活性和特异性中发挥作用。最后，我们将进行筛选分析，以确定毒素识别的靶细胞上的蛋白质。这一步骤对于促进细胞与细胞的接触至关重要，它定义了系统的特异性。我们将在这项研究中阐述的不同方面将有助于理解CDI系统在微生物群落中的作用。这方面的知识可以应用于生物膜社区，目前在土壤中，这是传播的来源B。人感染类鼻疽

DESCRIPTION (provided by applicant): The Gram-negative bacterium Burkholderia pseudomallei is a soil saprotroph and an emerging infectious disease agent. It is the causative agent of melioidosis, which can result in acute pulmonary disease, septicemia, and can be fatal if left untreated. Although naturally found in Southeast Asia and Northern Australia, it is of globl concern because of its potential to be weaponized. Bacteria typically live in polymicrobial communities and hence have evolved mechanisms to communicate, cooperate and compete with their neighbors. One such mechanism is the contact-dependent growth inhibition (CDI) system. This system is composed of two-partner secretion proteins, and is utilized by the bacterium to kill neighboring cells and potentially control the surrounding population. The main component of this system is a large surface exoprotein, BcpA, which contains a toxic C-terminus (CT). The CT is delivered to a target bacterial cell to induce death, unless the target cell contains an immunity protein to block the toxic activity. A hallmark feature of CDI systems is polymorphism among CTs and their cognate immunity proteins that protect in an allele specific manner. Studies in our laboratory have shown that the CDI system produced by the non-pathogen B. thailandensis is used for interbacterial competition and biofilm formation. In this proposal we will address several questions regarding Burkholderia-type CDI systems. First we will assess the ability of B. pseudomallei to utilize its CDI systems for interbacterial killing. W will then establish a role for CDI systems in interspecies killing when the bacterium comes into contact with closely related organisms. To achieve this we will evaluate interspecies competition between B. pseudomallei and B. thailandensis. Additionally, through studies using BcpA chimeric proteins, we will analyze regions of BcpA that potentially play a role in activity and specificity of the system. Lastly, we will perform screening analyses to identify the proteins on the target cell that are recognized by the toxin. This step is essential to promote cell-to-cell contact and it defines the specificity of the system. The different aspects that we will investigat in this study will contribute to the understanding of the role of CDI systems within a microbial community. This knowledge can be applied towards biofilm communities that are present in the soil, which is the source of transmission of B. pseudomallei to humans.