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是一个很大程度上未被探索的 一套可以被操纵来治疗或预防感染的治疗靶点。接触依赖型增长 抑制(CDI)是一种现象，在这种现象中，革兰氏阴性菌传递有毒的C末端， 在细胞与细胞直接接触时，将多态表面蛋白(BCPA)与邻近细菌的细胞质结合， 抑制目标受体细胞的生长，除非它产生适当的免疫蛋白(BCPI)。 虽然CDI系统几乎完全是因为它们调解细菌间的能力而被调查 竞争，我们之前的工作表明，CDI系统还通过以下方式促进细菌间的交流 诱导免疫受体细菌的特定基因表达和表型变化 适当的免疫蛋白，BCPI)。因此，CDI系统通过以下方式实现细菌自我/非自我辨别 几种相互重叠的机制，所有这些机制都可以用于治疗。然而，根本性的差距 由于对CDI系统分子功能的了解阻碍了对这些蛋白质如何影响的清楚理解 细菌的社会性，限制了基于CDI系统的抗菌剂、去污剂或疫苗的发展。 因此，我们的长期目标是确定CDI系统发挥作用的分子机制。 操纵这些蛋白质来治疗或预防传染病。我们的初步数据显示 伯克霍尔德氏菌为研究CDI系统生物学提供了一个易于处理的模式系统。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 细菌的行为。为了实现这些目标，该提案测试了伯克霍尔德里亚BCPA交易所是 受BCPA特定结构域、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展。建议的模型将通过以下方式进行测试：(1)确定 影响BCPA导入的接收方因素，以及(2)定义负责维护的BCPA域 向接受者提供适当的服务，并测试BCPA服务在伯克霍尔德里亚社区的作用。一起， 这项研究将为细菌细胞-细胞通讯的特定机制提供关键的见解， 在细菌感染的预防或治疗方面取得进展。

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.