Structure and function of Burkholderia contact-dependent growth inhibition (CDI) systems

摘要 细菌之间的社会相互作用影响传染病的传播和进展。分子 细菌-细菌竞争和交流的潜在机制也代表了一个很大程度上未被探索的 一组治疗靶点，可用于治疗或预防感染。接触依赖增长 抑制（CDI）是革兰氏阴性细菌递送大的， 多态性表面蛋白（BcpA）在细胞-细胞直接接触时进入相邻细菌的细胞质， 抑制靶向受体细胞的生长，除非其产生适当的免疫蛋白（BcpI）。 虽然CDI系统几乎专门针对其介导细菌间相互作用的能力进行了研究， 竞争，我们以前的工作表明，CDI系统也促进细菌间的通信， 诱导免疫受体细菌（产生免疫应答的细菌）中的特异性基因表达和表型变化。 适当的免疫蛋白（BcpI）。因此，CDI系统能够通过以下方式区分细菌自身/非自身： 几个重叠的机制，所有这些都可以在治疗上加以利用。然而，根本的差距 在CDI系统分子功能知识中，妨碍了对这些蛋白如何影响的清楚理解 细菌的社会性，并限制基于CDI系统的抗菌剂、去污剂或疫苗的开发。 因此，我们的长期目标是确定CDI系统功能的分子机制， 操纵这些蛋白质用于治疗或预防传染病。我们的初步数据显示 伯克霍尔德氏菌属提供了一个易于处理的模型系统，用于询问CDI系统生物学。这项建议 试图了解BcpA是如何从一种细菌传递到另一种细菌的，以及这个过程是如何形成的。 细菌行为为了实现这些目标，该提案测试了伯克霍尔德氏菌BcpA交换是 由BcpA特异性结构域、受体细胞受体和受体细胞的生理状态控制， 它们共同影响微生物群落的发育。该模型将通过以下方式进行测试：（1）识别 影响BcpA导入的接收方因素，以及（2）定义负责维护 适当的交付给收件人和测试的作用BcpA交付伯克霍尔德氏菌社区。在一起， 这项研究将为细菌细胞间通讯的特定机制提供重要的见解， 涉及预防或治疗细菌感染的进展。

ABSTRACT Social interactions between bacteria impact infectious disease transmission and progression. The molecular mechanisms underlying bacteria-bacteria competition and communication also represent a largely unexplored set of therapeutic targets that could be manipulated to treat or prevent infections. Contact-dependent growth inhibition (CDI) is a phenomenon in which Gram-negative bacteria deliver the toxic C-terminus of a large, polymorphic surface protein (BcpA) to the cytoplasm of neighboring bacteria upon direct cell-cell contact, inhibiting the growth of the targeted recipient cell unless it produces an appropriate immunity protein (BcpI). While CDI systems have been investigated almost exclusively for their ability to mediate inter-bacterial competition, our previous work indicated that CDI systems also facilitate inter-bacterial communication by inducing specific gene expression and phenotypic changes in immune recipient bacteria (those producing the appropriate immunity protein, BcpI). Thus, CDI systems enable bacterial self/nonself discrimination through several overlapping mechanisms, all of which could be exploited therapeutically. However, fundamental gaps in knowledge of CDI system molecular function prevent a clear understanding of how these proteins impact bacterial sociality and limit the development of CDI system-based antimicrobials, decontaminants, or vaccines. Thus, our long term goal is to identify the molecular mechanisms underlying CDI system function toward manipulating these proteins for the treatment or prevention of infectious disease. Our preliminary data show that Burkholderia species provide a tractable model system for interrogating CDI system biology. This proposal seeks to understand how BcpA is delivered from one bacterium to another and how this process shapes bacterial behavior. Toward these goals, the proposal tests the hypothesis that Burkholderia BcpA exchange is controlled by BcpA-specific domains, recipient cell receptors, and the physiological state of the recipient cell, which together impact microbial community development. The proposed model will be tested by (1) identifying the recipient factors that impact BcpA import, and (2) defining BcpA domains responsible for maintaining appropriate delivery to recipients and testing the role of BcpA delivery in Burkholderia communities. Together, this research will provide critical insight into a specific mechanism of bacterial cell-cell communication, leading to advancement in the prevention or treatment of bacterial infections.