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

7.项目摘要/摘要 蜂形复合体寄生虫包括许多广泛感染人和牲畜的病原体， 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，在宿主组织中 寄生虫会进行复制。因为顶端复合体只在宿主细胞内复制，所以入侵过程对 它们的存活和发病机制。侵袭是由特化分泌的蛋白质释放所介导的。 寄生虫顶端的细胞器、微线体和棒状体。微线体蛋白包括 支持寄生虫活动的粘附素，因此一旦寄生虫从复制中出现就会分泌 并开始向新的宿主细胞迁移以进行感染。相比之下，RHoptry只将其内容隐藏在 一旦寄生虫承诺入侵，宿主细胞就会识别。有证据表明，狂犬病的释放 含量取决于微线蛋白的先前分泌；然而，连接这些微线蛋白的分子事件 有两个过程是未知的。基于弓形虫模型的全基因组筛选， 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 名为夹具。我们的初步研究表明，钳夹对于杆状病毒的分泌是必要的，并且稳定 与两个微线体蛋白有关：SPATR，它以前被认为与入侵有关，以及一个 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 杆状病毒蛋白分泌所必需的复合体。我们的第一个目标是比较钳子的功能， SPATR和CLIP；研究它们是如何齐聚的；并阐明复合体之间的关系 形成和杆状分泌物。在我们的第二个目标中，我们将鉴定和表征寄主和寄生虫的蛋白质。 与夹子入侵复合体相互作用。最后，我们的第三个目标将公正地看待宿主细胞 刺激杆状蛋白分泌的因子，它可能与钳制复合体相交来调节这一点 顶端复合体入侵的关键一步。基于涉及的寄生虫蛋白质的保守性，我们预计 所揭示的原理将推广到这一门，并广泛地告知我们对这些的理解 感染剂。

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.