Contact-Dependent Interbacterial Signaling in Burkholderia

 描述（由申请方提供）：非致病性和致病性伯克霍尔德菌，包括机会性感染引起的洋葱伯克霍尔德菌复合体的成员，编码产生接触依赖性生长抑制（CDI）系统蛋白的基因。CDI是一种广泛存在的现象，其中革兰氏阴性细菌使用多态性表面暴露的外蛋白的毒性C末端来抑制细胞-细胞接触时易感细菌的生长。外蛋白毒素被递送到靶细胞的细胞质， 通过产生小的免疫蛋白来预防。我们以前证明，除了它们在细菌间竞争中的作用外，由bcpAIOB编码的泰国伯克霍尔德氏菌中的CDI系统蛋白介导生物膜形成。这需要推定的核酸酶活性的BcpA毒性外蛋白，但是独立的细菌间的杀伤，表明生物膜形成在B。thailandensis涉及BcpA的一个未表征的功能。初步数据表明，bcpA 10 B介导B中的细菌间信号传导。thailandensis，导致免疫靶细菌中基因表达的变化。鉴于这些数据和CDI系统的保守性，其他伯克霍尔德氏菌中的CDI系统似乎也在细菌间信号传导中起作用，并可能在感染期间发挥作用。为了理解CDI系统介导的信号传导的作用，该提案将测试的假设，BcpA毒素传递到免疫靶细胞与特定的周质和细胞质因子相互作用，导致全球基因表达的变化，并代表一个有用的治疗靶点致病性伯克霍尔德氏菌。目的1中提出的实验将继续研究B中bcpA 10 B介导的细菌间信号传导的机制。thailandensis，定义受影响的基因调控途径，并确定所需的BcpA区域，以及其他必要的信号传导因子。目标2中的研究将探索CDI系统的作用及其作为致病性洋葱伯克霍尔德菌复合菌株的治疗方法的潜力。这些研究代表了对革兰氏阴性菌中可能广泛存在的现象的首次调查，并将致力于解决对新药物靶标和抗菌剂的基本需求。

 DESCRIPTION (provided by applicant): Both non-pathogenic and pathogenic Burkholderia, including members of the opportunistic infection-causing Burkholderia cepacia complex, encode genes to produce contact-dependent growth inhibition (CDI) system proteins. CDI is a widespread phenomenon in which Gram-negative bacteria use the toxic C-terminus of a polymorphic surface-exposed exoprotein to inhibit the growth of susceptible bacteria upon cell-cell contact. The exoprotein toxin is delivered to the cytoplasm of target cells and autoinhibition is prevented by production of a small immunity protein. We previously demonstrated that, in addition to their role in interbacterial competition, the CDI system proteins in Burkholderia thailandensis, encoded by bcpAIOB, mediate biofilm formation. This requires the putative nuclease activity of the BcpA toxic exoprotein, but is independent of interbacterial killing, suggesting that biofilm formation in B. thailandensis involves an uncharacterized function of BcpA. Preliminary data suggest that bcpAIOB mediate interbacterial signaling in B. thailandensis, leading to a change in gene expression in immune target bacteria. Given these data and the conservation of CDI systems, it seems likely that CDI systems in other Burkholderia also function in interbacterial signaling and could play a role during infection. Toward understanding the role of CDI system-mediated signaling, this proposal will test the hypothesis that BcpA toxin delivered to an immune target cell interacts with specific periplasmic and cytoplasmic factors, leading to global gene expression changes, and represents a useful therapeutic target in pathogenic Burkholderia. Experiments proposed in Aim 1 will continue to investigate the mechanism of bcpAIOB-mediated interbacterial signaling in B. thailandensis, defining the affected gene regulation pathways and identifying required regions of BcpA, as well as other factors necessary for signaling. Studies in Aim 2 will explore the role of CDI systems and their potential for exploitation as therapies in pathogenic Burkholderia cepacia complex strains. These studies represent the first investigation of what may be a widespread phenomenon in Gram-negative bacteria and will work toward addressing an essential need for new drug targets and antimicrobials.