Intracellular cargo transport in Toxoplasma gondii

项目摘要 细胞内货物运输是一个重要的和普遍存在的细胞过程，发生在所有真核细胞。然而，在这方面， 货物运输的机制仅在少数“模式”物种中被广泛研究， 在我们对其他真核生物群体的货物运输的理解中留下了很大的知识空白。我的实验室 最近在顶复门原生动物寄生虫中发现了一种新的货物运输机制 弓形虫;阐明这种细胞内运输系统的机制细节是重点 在这个提议上。T.弓形虫是顶复门的一部分，其中含有大量的医学 重要的寄生虫包括疟原虫属，疟疾和隐孢子虫属的病原体。的 会导致危及生命的疟疾因此，除了提供对不同机制的深入了解之外， 货物运输存在于进化分歧的真核生物，了解货物的分子基础， 顶复门中的转运可能导致抗寄生虫药物开发的潜在靶点的鉴定。 我们先前发表的和初步的数据表明，两种细胞骨架蛋白，肌动蛋白和 非常规肌球蛋白（MyoF）是广泛的细胞内货物运动所必需的。虽然 MyoF具有结构相似的货物转运蛋白肌球蛋白V，我们证明，MyoF 并不直接与其膜结合货物结合。相反，MyoF是潜在肌动蛋白的组织者， 细胞骨架为了全面了解这种货物运输机制，我们的目标是确定 货物运输所需的其他分子参与者，并确定这些分子参与运输的机制。 蛋白质与MyoF和肌动蛋白协作驱动货物移动。具体来说，我们将回答以下问题 悬而未决的问题：MyoF的活性是如何调节的？囊泡货物如何与肌动蛋白结合 细胞骨架是否有其他蛋白质与MyoF合作来控制组织和动力学 肌动蛋白细胞骨架为了解决这些问题，我们将利用三个不同的，但互补， 实验方法：（1）寄生虫遗传学和细胞生物学，（2）活细胞成像和定量囊泡 追踪和（3）体外生物物理方法。我的实验室位于 寄生虫学和分子发动机领域之间的联系利用这些跨学科的方法使我们成为理想的 定位于为这个未充分研究的过程提供新的见解。

PROJECT SUMMARY Intracellular cargo transport is a vital and ubiquitous cellular process that occurs in all eukaryotic cells. However, the mechanisms of cargo transport have only been extensively investigated in a small number of “model” species, leaving a large knowledge gap in our understanding of cargo transport in other eukaryotic groups. My laboratory has recently uncovered a novel mechanism of cargo transport in the Apicomplexan protozoan parasite Toxoplasma gondii; elucidating the mechanistic details underlying this intracellular transport system is the focus on this proposal. T. gondii is part of the phylum Apicomplexan, which contains a large number of medically important parasites including Plasmodium spp., the causative agent of malaria and Cryptosporidium spp. that can cause life-threatening diarrheal disease. Thus, in addition to providing insight into the diverse mechanisms of cargo transport that exist in evolutionary divergent eukaryotes, understanding the molecular basis of cargo transport in Apicomplexa could lead to the identification of potential targets of anti-parasitic drug development. Our previously published and preliminary data demonstrate that two cytoskeletal proteins, actin and an unconventional myosin (MyoF) are required for the movement of a wide range of intracellular cargo. Although MyoF has structural similarity to the well-characterized cargo transporter myosin V, we demonstrate that MyoF does not associate directly with its membrane bound cargo. Instead, MyoF is an organizer of the underlying actin cytoskeleton. In order to gain a complete picture of this cargo transport mechanism, our goal is to identify additional molecular players that are required for cargo transport and to define the mechanisms by which these proteins drive cargo movement in collaboration with MyoF and actin. Specifically, we will answer the following outstanding questions: How is the activity of MyoF regulated? How does vesicular cargo associate with the actin cytoskeleton? Are there additional proteins that cooperate with MyoF to control the organization and dynamics of the actin cytoskeleton? To address these questions, we will utilize three distinct, yet complementary, experimental approaches: (1) parasite genetics and cell biology, (2) live cell imaging and quantitative vesicle tracking and (3) in vitro biophysical approaches. My laboratory occupies a unique niche at the intersection between parasitology and molecular motors fields. Utilizing these interdisciplinary approaches makes us ideally positioned to provide new insights into this understudied process.