Control of parasite invasion by a microneme protein complex conserved in Apicomplexans

7.项目总结/摘要 顶复门寄生虫包括许多广泛的人类和牲畜感染的病原体， 例如疟疾和弓形虫病。这些疾病是由宿主组织的破坏引起的， 寄生虫复制。由于顶复门只在宿主细胞内复制，因此入侵过程对宿主细胞的生长至关重要。 他们的生存和发病机制。入侵是由特定的分泌细胞释放蛋白质介导的。 寄生虫顶端的细胞器，微丝和棒状体。蛋白质组包括 支持寄生虫运动并因此在寄生虫复制后立即分泌的粘附素 并开始向新的宿主细胞迁移以进行感染。相比之下，棒状体只在 一旦寄生虫入侵，宿主细胞识别。有证据表明释放棒状体 含量取决于微线体蛋白的先前分泌;然而，连接这些微线体蛋白的分子事件 两个过程是未知的。基于在模型顶复门弓形虫中的全基因组筛选， 我们的实验室最近发现了一种保守的微线体蛋白，它是入侵人类细胞所必需的，我们 名为CLAMP。我们的初步研究表明CLAMP是棒状体分泌所必需的， 与两种微线体蛋白相关：SPATR，以前与入侵有关， 我们称之为CLIP的未知蛋白质。我们假设这些相互作用代表了一种新的入侵 棒状体蛋白分泌所必需的复合物。我们的第一个目的是比较CLAMP的功能， SPATR和CLIP;研究它们如何寡聚化;并阐明复合物之间的关系 形成和棒状体分泌。在我们的第二个目标，我们将确定和表征宿主和寄生虫蛋白质 与CLAMP入侵复合体相互作用。最后，我们的第三个目标是对宿主细胞进行公正的观察 刺激棒状体蛋白分泌的因子，其可能与CLAMP复合物交叉以调节这种分泌。 是顶复体入侵的关键步骤基于所涉及的寄生虫蛋白的保守性，我们预计， 所揭示的原理将普遍适用于动物门，并广泛地告知我们对这些原理的理解。 传染源

7. PROJECT SUMMARY/ABSTRACT Apicomplexan parasites include the etiologic agents of many widespread infections of humans and livestock, such as malaria and toxoplasmosis. These diseases are caused by destruction of the host tissues in which the parasites replicate. Because apicomplexans only replicate inside host cells, the process of invasion is critical to their survival and pathogenesis. Invasion is mediated by the release of proteins from specialized secretory organelles at the apical end of the parasite, the micronemes and rhoptries. Microneme proteins include adhesins that support parasite motility and are therefore secreted as soon as parasites emerge from replication and start migrating towards new host cells to infect. Rhoptries, by contrast, secrete their contents only upon host cell recognition once parasites have committed to invasion. Evidence suggests that the release of rhoptry contents depends on the prior secretion of microneme proteins; however, the molecular events that link these two processes are unknown. Based on a genome-wide screen in the model apicomplexan Toxoplasma gondii, our lab recently identified a conserved microneme protein necessary for invasion of human cells, which we named CLAMP. Our preliminary studies show that CLAMP is necessary for rhoptry secretion and stably associates with two microneme proteins: SPATR, which was previously implicated in invasion, and an uncharacterized protein we call CLIP. We hypothesize that these interactions represent a novel invasion complex necessary for rhoptry protein secretion. Our first aim is to compare the functions of CLAMP, SPATR, and CLIP; investigate how they oligomerize; and elucidate the relationship between complex formation and rhoptry secretion. In our second aim, we will identify and characterize host and parasite proteins that interact with the CLAMP invasion complex. Finally, our third aim will take an unbiased look at the host cell factors that stimulate rhoptry protein secretion, which may intersect with the CLAMP complex to regulate this key step in apicomplexan invasion. Based on the conservation of the parasite proteins involved, we expect that the principles uncovered will be generalizable to the phylum and broadly inform our understanding of these infectious agents.