Identification and functional characterization of proteins of the mitochondrial tRNA import pathway of Toxoplasma gondii

弓形虫线粒体 tRNA 输入途径蛋白的鉴定和功能表征

• 批准号: BB/N003675/1
• 负责人: Lilach Sheiner
• 金额: $ 46.17万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FN003675%2F1
• 关键词: Identification; functional; characterization; proteins; mitochondrial

Apicomplexa is a group of parasites that have extremely high infection rate in humans and animals and that is very harmful. The most deadly disease caused by an apicomplexan is malaria that kills millions yearly in developing countries. Other parasites from the group are also responsible for diseases in people with compromised immune systems, like AIDS patients. Still more, apicomplexans cause disease in agricultural animals, resulting in major economic harm and damage to humans food supply. Toxoplasma, for example, is one of the most frequent causes for abortions in sheep.These small, single-celled parasites live and multiply within the larger cells of their human or animal host. Accordingly, these parasites evolved elaborate tactics to minimize exposure to host defence systems while still harvesting their needed metabolites from this hostile environment. Two organelles within each parasite, called the mitochondrion and the apicoplast, play crucial roles in this struggle by providing essential centres of parasite metabolism. Consequently their function is essential and their maintenance is tightly regulated and synchronized with the parasites' proliferation. Each parasite possesses one mitochondrion that divides and changes morphology in full synchrony with the parasite cell division. This is unlike the situation in human and animal cells where the many mitochondria found in each cell replicate, change and function independent of the cell division.Mitochondria were acquired via endosymbiosis whereby one cell was engulfed by another and was gradually enslaved to become a dependent organelle. Molecular transport mechanisms through which the organelle and the cells could exchange materials had to evolve to allow this take-over. One such example is mitochondrial tRNA import (MITI). Since the mitochondria kept some of the genome of its ancestor it needs tRNAs to express its genes to functional proteins. While in most organisms the mitochondria still retain its own tRNA genes, in Apicomplexa all tRNAs are encoded in the nucleus of the cell and the mitochondrion must import all the tRNAs it needs from the cell cytosol, making MITI absolutely crucial for parasite survival. This pivotal role highlights MITI as a key player in controlling the tight synchrony between parasite and mitochondrion division. Despite the crucial important of MITI in the evolution of mitochondria, scientists have only described MITI systems in detail in a handful of organisms, resulting in a very limited understanding of its origin and development. Moreover, despite the essential role of MITI in the control of mitochondrial function in Apicomplexa, its composition and functional mechanism in these parasites are entirely elusive. In this study integrated and complementary approaches will be used to catalogue and analyse the components of the MITI machinery in the most well developed experimental system in Apicomplexa, Toxoplasma gondii. A detailed model of the MITI composition and organization will be generated via tagging of individual components and dissecting their interaction with each other and with the RNA in transit. The function of the individual components, and of MITI as a whole, will be analysed by genetically removing one component at a time. Not only will this provide the first description of MITI in a new group of organisms, it will also developed our understanding of MITI evolution, and how in the case of these parasites it supports their deadly lifestyle. A thorough understanding of the apicomplexa MITI system will also provide a new potential avenue for the design of novel therapeutic strategies to fight diseases like toxoplasmosis and malaria.

顶复虫属是一组在人类和动物中感染率极高的寄生虫，危害极大。由顶复门动物引起的最致命的疾病是疟疾，每年在发展中国家造成数百万人死亡。该组织的其他寄生虫也是免疫系统受损的人的疾病，如艾滋病患者。此外，顶复门在农业动物中引起疾病，导致重大的经济损失和对人类食物供应的破坏。例如，弓形虫是导致绵羊流产的最常见原因之一，这些小的单细胞寄生虫在人类或动物宿主的较大细胞内生活和繁殖。因此，这些寄生虫进化出了精心设计的策略，以尽量减少暴露于宿主防御系统，同时仍然从这种恶劣的环境中收获它们所需的代谢物。每种寄生虫体内的两个细胞器，称为顶体和顶质体，通过提供寄生虫代谢的重要中心，在这场斗争中发挥着至关重要的作用。因此，它们的功能是必不可少的，它们的维持受到严格的调节，并与寄生虫的增殖同步。每一种寄生虫都有一个能与寄生虫细胞分裂完全同步地分裂和改变形态的小孢子。这与人类和动物细胞中的情况不同，在人类和动物细胞中，每个细胞中的许多线粒体都独立于细胞分裂而复制、变化和发挥功能。线粒体是通过内共生获得的，其中一个细胞被另一个细胞吞噬，并逐渐被奴役，成为一个依赖的细胞器。细胞器和细胞交换物质的分子运输机制必须进化才能允许这种接管。一个这样的例子是线粒体tRNA输入（MITI）。由于线粒体保留了其祖先的一些基因组，因此需要tRNA将其基因表达为功能蛋白质。虽然在大多数生物体中，线粒体仍然保留其自身的tRNA基因，但在顶复门中，所有的tRNA都在细胞核中编码，而线粒体必须从细胞质中输入所需的所有tRNA，这使得MITI对寄生虫的生存至关重要。这一关键作用突出了MITI作为控制寄生虫和寄生虫分裂之间紧密同步的关键参与者。尽管MITI在线粒体进化中至关重要，但科学家们只在少数生物中详细描述了MITI系统，导致对其起源和发展的了解非常有限。此外，尽管MITI在顶复门中控制线粒体功能的重要作用，但其在这些寄生虫中的组成和功能机制完全难以捉摸。在这项研究中，综合和互补的方法将被用来编目和分析的MITI机械的组件在最发达的实验系统中Apicomplexa，弓形虫。MITI组成和组织的详细模型将通过标记单个组件并剖析它们彼此之间以及与运输中的RNA的相互作用来生成。将通过每次从基因上去除一种成分来分析各个成分和MITI整体的功能。这不仅将首次在一组新的生物体中描述MITI，还将发展我们对MITI进化的理解，以及在这些寄生虫的情况下，它如何支持他们致命的生活方式。对顶复体MITI系统的深入了解也将为设计新的治疗策略以对抗弓形虫病和疟疾等疾病提供新的潜在途径。

项目成果

Protein Import into the Endosymbiotic Organelles of Apicomplexan Parasites.

• DOI: 10.3390/genes9080412
• 发表时间: 2018-08-14
• 期刊: Genes
• 影响因子: 3.5
• 作者: Mallo N;Fellows J;Johnson C;Sheiner L
• 通讯作者: Sheiner L

Mitochondrial behaviour throughout the lytic cycle of Toxoplasma gondii.

• DOI: 10.1038/srep42746
• 发表时间: 2017-02-16
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Ovciarikova J;Lemgruber L;Stilger KL;Sullivan WJ;Sheiner L
• 通讯作者: Sheiner L

ATP synthase hexamer assemblies shape cristae of Toxoplasma mitochondria.

• DOI: 10.1038/s41467-020-20381-z
• 发表时间: 2021-01-05
• 期刊: Nature communications
• 影响因子: 16.6
• 作者: Mühleip A;Kock Flygaard R;Ovciarikova J;Lacombe A;Fernandes P;Sheiner L;Amunts A
• 通讯作者: Amunts A

Complexome profile of Toxoplasma gondii mitochondria identifies divergent subunits of respiratory chain complexes including new subunits of cytochrome bc1 complex.

• DOI: 10.1371/journal.ppat.1009301
• 发表时间: 2021-03
• 期刊: PLoS pathogens
• 影响因子: 6.7
• 作者: Maclean AE;Bridges HR;Silva MF;Ding S;Ovciarikova J;Hirst J;Sheiner L
• 通讯作者: Sheiner L

Two essential Thioredoxins mediate apicoplast biogenesis, protein import, and gene expression in Toxoplasma gondii.

• DOI: 10.1371/journal.ppat.1006836
• 发表时间: 2018-03
• 期刊: PLoS pathogens
• 影响因子: 6.7
• 作者: Biddau M;Bouchut A;Major J;Saveria T;Tottey J;Oka O;van-Lith M;Jennings KE;Ovciarikova J;DeRocher A;Striepen B;Waller RF;Parsons M;Sheiner L
• 通讯作者: Sheiner L