Examining a Unique Contractile Injection System Mediating Host-Microbe Interactions

项目摘要 人类微生物群中的细菌通常对宿主有利。然而，一些不平衡的 类杆菌等细菌群可导致肥胖和肠炎等疾病 疾病。目前微生物组领域的一个重大挑战是识别由 微生物群打破了健康与疾病之间的平衡。对这些知识的缺乏 产品是改善调节我们的微生物群(例如粪便)的治疗方法的一个重大障碍 移植)--目前正在紧张调查的一个领域。我实验室的目标是找出 来自促进健康或疾病的正常微生物组细菌的产品，并确定其 行动机制。为此，我们发现了一个以前没有描述过的收缩家族 细菌用来自然促进无脊椎动物宿主发育的注射系统 (一种名为雅致水蚤的管虫)。收缩注射系统通过注射来工作 刺激效应蛋白进入宿主细胞，促进发育或引发疾病。这 新的收缩注射系统家族是独一无二的，因为它们专门针对真核细胞 生物体(如阿米巴、昆虫、管虫)。到目前为止，这一家族的注射系统并不是 已知存在于与人类相关的细菌中。然而，我们最近发现，肠道 来自美国和欧洲的几乎所有成人(99%)的微生物群携带着密切的 相关的，但以前未描述的收缩注射系统。此外，我们的体外实验 实验表明类杆菌收缩注射系统促进人类细胞 细胞增殖和炎症反应。在这项提案中，我们将为 确定这些新发现的收缩注射系统对人类健康的影响。 我们的中心假设是，这一新的注射系统家族包括一种关键的交互手段 在微生物群细菌和宿主之间，促进发育和疾病取决于 部署的效应器和交互的上下文。今后五年的工作重点是(项目 1)研究4亚型CIS效应器蛋白的功能并将效应器活性与 宿主的细胞反应；(项目2)确定这类CIS如何与真核细胞结合 使用结构上类似于真核钙粘蛋白蛋白的纤维；以及(项目3)阐明 应用冷冻法研究人肠道类杆菌4亚型CIS的结构与功能关系 电子断层扫描和荧光显微镜。我们的成果将为技术奠定基础 利用拟杆菌属细菌及其收缩注射系统作为益生菌治疗 调节人体微生物群和宿主健康。

Project Summary Bacteria within the human microbiome typically benefit the host. However, an imbalance of some bacteria groups such as Bacteroidales can lead to diseases like obesity and inflammatory bowel disease. A current grand challenge in the microbiome field is to identify products produced by microbiome bacteria that tip this health-to-disease balance. The lack of knowledge about these products is a significant barrier to improving therapies that modulate our microbiome (e.g. fecal transplants)—a current area of intense investigation. The objective of my laboratory is to identify products from normal microbiome bacteria that promote health or disease and determine their mechanisms of action. To this end, we discovered a previously undescribed family of Contractile Injection System that bacteria use to naturally promote the development of an invertebrate host (a tubeworm called Hydroides elegans). Contractile Injection Systems work by injecting stimulatory effector proteins into host cells that either promote development or elicit disease. This new family of Contractile Injection System is unique because they exclusively target eukaryotic organisms (e.g. amoeba, insects, tubeworms). Until now, this family of Injection System was not known to occur in human-associated bacteria. However, we recently discovered that the gut microbiomes of nearly all human adults (>99%) from the United States and Europe carry a closely related, yet previously undescribed Contractile Injection System. Moreover, our in vitro experiments show that Contractile Injection Systems in Bacteroides bacteria promote human cell line proliferation and inflammatory responses. In this proposal, we will lay the foundation for determining the impact of these newly discovered Contractile Injection Systems on human health. Our central hypothesis that this new Injection System family comprise a key means of interaction between microbiome bacteria and host, promoting both development and disease depending on the effectors deployed and context of interaction. Efforts for the next five years focus on (Project 1) investigating the functions of Subtype-4 CIS effector proteins and link effector activity with the host’s cellular responses; (Project 2) determining how this class of CIS binds to eukaryotic cells using fibers that structurally resemble eukaryotic cadherin proteins; and (Project 3) elucidating the structure-function relationship of Subtype-4 CIS from human gut Bacteroidales using cryo- electron tomography and fluorescence microscopy. Our results will lay a foundation for technology employing Bacteroidales bacteria and their Contractile Injection Systems as probiotics to modulate the human microbiome and host health.