Role of a novel auto-protease domain in antibacterial toxin delivery

项目摘要 接触依赖性生长抑制（CDI）是细菌间竞争的重要机制 在多种革兰氏阴性菌中发现，包括许多重要的人类病原体。CDI是 由CdiB/CdiA家族的双伴侣分泌蛋白介导，其被认为组装为二元 在细胞表面的复合物。CdiA形成细丝以远离抑制剂细胞突出以结合至 敏感细菌上的受体。结合受体后，CdiA将其C-末端毒素结构域（CdiA-CT） 进入目标细胞。CDI系统还编码特异性结合CdiA-CT的CdiI免疫蛋白 并中和毒素活性以保护细胞免受自身抑制。CdiA-CT/CdiI序列非常 可变的，在细菌基因组中识别出>130种不同的毒素/免疫蛋白序列类型。CdiA-CT 毒素是模块化的，并且可以在CdiA蛋白之间交换以产生功能嵌合体。这些 观察表明，许多不同种类的有毒货物可以被递送到靶细胞的细胞质中， 细菌本申请寻求确定使这一点成为可能的分子和结构基础。 显著的功能可塑性。我们将结合分子遗传学，生物化学和结构学 的方法，以获得深入了解CdiA的组成域之间的功能相互作用。这 研究将显着增加我们对CdiA功能的机械理解，并可以为新的研究提供信息。 抗微生物治疗的策略。

Project summary Contact-dependent growth inhibition (CDI) is an important mechanism of inter-bacterial competition found in a wide variety of Gram-negative bacteria, including many important human pathogens. CDI is mediated by the CdiB/CdiA family of two-partner secretion proteins, which are thought to assemble as a binary complex on the cell surface. CdiA forms a thin filament to projects away from the inhibitor cell to bind to receptors on susceptible bacteria. After binding receptor, CdiA delivers its C-terminal toxin domain (CdiA-CT) into the target cell. CDI systems also encode CdiI immunity proteins, which specifically bind to the CdiA-CT and neutralize toxin activity to protect the cell from auto-inhibition. CdiA-CT/CdiI sequences are extraordinarily variable, with >130 distinct toxin/immunity protein sequence types recognized in bacterial genomes. CdiA-CT toxins are modular and can be exchanged between CdiA proteins to generate functional chimeras. These observations indicate that many different kinds of toxic cargo can be delivered into the cytoplasm of target bacteria. This application seeks to determine the molecular and structural underpinnings that enable this remarkable functional plasticity. We will use a combination of molecular genetic, biochemical and structural approaches to gain insight into the functional interactions between the constituent domains of CdiA. This research will significantly increase our mechanistic understanding of CdiA function and could inform novel strategies for antimicrobial therapy.