The role of secreted effector proteins in Chlamydia trachomatis invasion

项目概要 沙眼衣原体 (C.t.) 是非先天性失明的主要原因，也是最常见的性病 世界范围内传播的细菌感染，如果不及时治疗可能会导致严重后果。全部 衣原体是专性细胞内细菌，因此进入宿主细胞对于病原体至关重要 完成其复制周期并增殖。尽管入侵过程具有关键性质，但分子 有关 C.t. 的机制和细节强行进入非吞噬细胞仍然是一个很大的知识 差距。当前模型的一个主要前提表明，通过交付预先包装的物品来促进入侵 传统的 III 型分泌系统 (cT3SS) 效应蛋白在病原体进入宿主细胞之前进入宿主细胞。我们 假设这些 cT3SS 效应子的一个子集通过协调宿主细胞骨架的主动颠覆 直接操纵肌动蛋白动力学的关键调节因子。我们实验室的新数据表明 cT3SS 效应蛋白 TmeA 与成核促进因子 N-WASP 结合，我们证明这两者都是必需的 为了入侵。在目标 1 中，我们将机械地确定 TmeA 如何调节 N-WASP 并确定是否 这种相互作用促进了可能有助于细菌进入的关键膜特征，例如；膜褶皱， 基座形成和丝状伪足动力学。鉴于入侵对细菌增殖的本质性质和 生存，C.t.可能采取多种入侵措施。在目标 2 中，我们将评估复杂的相互作用 TarP、TepP 和 TmeA 之间的关系，揭示其效应子功能的最终分子效应并描述 这些效应子所针对的看似不同的途径如何汇聚以确保衣原体入侵。 此外，我们将确定其他 cT3SS 效应子是否仅以侵入性 EB 形式表达 衣原体是侵入非吞噬细胞所必需的。细菌和宿主的详细表征 在 C.t. 期间促进肌动蛋白细胞骨架重组所需的蛋白质。入侵将提供一个整体 细胞内病原体（例如 C.t.）如何协调细胞骨架调节因子的破坏以入侵宿主 细胞。

Project Summary Chlamydia trachomatis (C.t.) is the leading cause of non-congenital blindness and the most prevalent sexually transmitted bacterial infection in the world, which if left untreated can result in severe consequences. All chlamydiae are obligate intracellular bacteria and thus gaining entry into a host cell is essential for the pathogen to complete its replicative cycle and proliferate. Despite the critical nature of the invasion process, the molecular mechanisms and details regarding how C.t. forces its way into non-phagocytic cells remains a large knowledge gap. A major premise of the current model suggests that invasion is facilitated by delivery of prepackaged conventional type III secretion system (cT3SS) effector proteins into the host cell prior to pathogen entry. We hypothesize that a subset of these cT3SS effectors coordinate active subversion of the host cytoskeleton through direct manipulation of key regulators of actin dynamics. New data from our laboratory indicates that the cT3SS effector protein TmeA binds to the nucleation promoting factor N-WASP, both of which we show are essential for invasion. In Aim 1, we will mechanistically determine how TmeA regulates N-WASP and determine whether this interaction promotes key membrane features that likely aid in bacterial entry such as; membrane ruffling, pedestal formation, and filopodial dynamics. Given the essential nature of invasion to bacterial proliferation and survival, C.t. likely employs multiple measures for invasion. In Aim 2, we will evaluate the complex interplay between TarP, TepP, and TmeA and reveal the ultimate molecular effects of their effector function and describe how the seemingly disparate pathways targeted by these effectors converge to assure chlamydial invasion. Furthermore, we will determine whether other cT3SS effectors, only expressed in the invasive EB form of chlamydia, are necessary for invasion of non-phagocytic cells. Detailed characterization of the bacterial and host proteins required to promote reorganization of the actin cytoskeleton during C.t. invasion will provide a holistic view of how intracellular pathogens, such as C.t., coordinate subversion of cytoskeletal regulators to invade host cells.