Protein targeting and secretion in Toxoplasma

描述(申请人提供)：弓形虫是一种广泛传播的 引起艾滋病患者重症脑炎的机会性病原体。弓形虫 也是研究相关心尖复合体的实验模型系统 在艾滋病中重要的寄生虫包括隐孢子虫、环孢子虫、等孢子虫、 疟疾的病原体--疟原虫。顶端复合体的复制 寄生虫只发生在其宿主的细胞内，在专门的 入侵过程中形成的隔室--寄生液泡。蛋白 分泌物与宿主细胞的侵袭密切相关， 寄生液泡的建立/维持。就像入侵一样 这些步骤对于寄生虫复制至关重要，也可能意味着潜在的 抗寄生虫药物或疫苗开发的目标。这项建议旨在 研究蛋白质分泌和靶向在宿主细胞侵袭和转移中的作用 液泡成熟。弓形虫的分泌器官高度多样化， 其分泌物来自三组细胞器：微线体、棒状体、 和致密的颗粒。我们将描述往返于这些区域的蛋白质运输的特征 使用活体报告基因的细胞器。使用删除的序列映射 分析和更微妙的点突变将使我们能够建立 分子信号参与了这个分选过程。有条件的变种人将是 分离于富含分泌物的表型筛选 记者。分离的突变寄生虫将被用来确定分泌物是否 入侵事件的本质或巧合。突变分析也将 为个人分泌物的功能提供关键信息 涉及细胞器。

DESCRIPTION (provided by applicant): Toxoplasma gondii is a wide-spread opportunistic pathogen causing severe encephalitis in AIDS patients. T. gondii is also an experimental model system for the study of related apicomplexan parasites important in AIDS including Cryptosporidium, Cyclospora, Isospora, and Plasmodium the causative agent of malaria. Replication of apicomplexan parasites takes place only inside the cells of its host, within a specialized compartment formed during invasion - the parasitophorous vacuole. Protein secretion is tightly associated with host-cell invasion and establishment/maintenance of the parasitophorous vacuole. As invasion is essential to parasite replication these steps might also pesent potential targets for anti-parasite drug or vaccine development. This proposal aims to study the role of protein secretion and targeting in host cell invasion and vacuole maturation. The secretory apparatus in T gondii is highly diversified, with secretion occurring from three sets of organelles: micronemes, rhoptries, and dense granules. We will characterize protein trafficking to and from these organelles using in vivo reporter genes. Sequence mapping using deletion analysis and more subtle point-mutations will permit us to establish the molecular signals involved in this sorting process. Conditional mutants will be isolated in a phenotypic screen enriching for the accumulation of a secretory reporter. Isolated mutant parasites will be used to establish if secretion is essential or coincidental with the invasion event. Mutant analysis will also provide critical information towards the function of the individual secretory organelles involved.