Membrane and host cytoskeleton reorganization during malaria parasite egress from erythrocytes

疟疾寄生虫从红细胞中排出期间的膜和宿主细胞骨架重组

• 批准号: MR/P010288/1
• 负责人: Helen Saibil
• 金额: $ 56.28万
• 依托单位: Birkbeck, University of London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FP010288%2F1
• 关键词: Membrane; host; cytoskeleton; reorganization; during

Malaria is a major global killer, most deadly for children in the developing world. Of the five species that infect humans, Plasmodium falciparum is the most lethal. Although there are currently effective anti malarial drugs, the appearance and spread of resistant strains of P falciparum pose an increasing threat. The parasite has a complex life cycle with several different stages in its mosquito and human hosts, but the clinical symptoms in humans arise from waves of parasite release during the asexual blood stages, in which parasites invade red blood cells and multiply within an internal membrane compartment called a vacuole. The growing parasites hijack their host blood cells, consume their haemoglobin, and redirect the cell activity for the benefit of the parasite. Of particular importance, the parasite exports some of its own proteins to build new structures on the surface of the blood cell. A uniquely lethal aspect of P. falciparum is that it creates surface protrusions (called knobs) on the blood cell that make it adhere to the lining of blood vasculature. This prevents the infected cells from being captured and destroyed by the spleen, but can also block brain blood capillaries, the main cause of death in malaria infection. Once they have matured, 16-24 daughter parasites break through their surrounding vacuole membrane as well as the red blood cell membrane (a process collectively called egress) to enter the bloodstream, where they immediately invade a fresh round of blood cells. The processes of invasion, adhesion and egress are regulated through a cascade of enzyme reactions, as well as expression and transport of structural components. Some of these components are unique to malaria, making them potential targets for future drug development. Currently, most of them are poorly characterised.In this project, we focus on the steps by which the mature parasites break through the two bounding membranes to undergo egress. A highly regulated series of steps leads to the explosive release of parasites from the blood cell. To examine these membrane breakage events in detail, we use electron microscopy to image at nanoscale resolution the three-dimensional structures of the infected cells during the late stages of parasite development. This imaging is combined with use of parasite mutants and drug-like molecules and enzyme inhibitors to trap the parasites at different steps of egress. This approach has already led us to discover a new, initial step in egress that had not been previously detected. We now know that the process begins with the parasites causing the membrane surrounding their vacuole to become leaky. Subsequently, this membrane is completely disrupted, allowing the parasites to move freely inside the blood cell. Shortly after that, the blood cell membrane itself becomes leaky and then finally the cell membrane and its underlying cytoskeleton rupture to allow the parasites to escape and invade new host blood cells. With recent advances in gene editing technology, it has now become possible to conditionally modify gene expression in P. falciparum, and we will use this powerful technology to probe the molecular nature, functions and subcellular localisations of key malaria components involved in the sequence of steps during egress. The results of these studies could form the basis for future development of novel therapeutics.

疟疾是一个主要的全球杀手，对发展中国家的儿童来说最致命。在感染人类的五种疟原虫中，恶性疟原虫是最致命的。虽然目前有有效的抗疟药物，但恶性疟原虫耐药株的出现和传播构成了越来越大的威胁。这种寄生虫有一个复杂的生命周期，在蚊子和人类宿主中有几个不同的阶段，但人类的临床症状是由无性血液阶段的寄生虫释放波引起的，其中寄生虫侵入红细胞并在称为空泡的内膜隔室中繁殖。不断增长的寄生虫劫持其宿主的血细胞，消耗其血红蛋白，并重新定向细胞活动以利于寄生虫。特别重要的是，寄生虫输出一些自己的蛋白质，在血细胞表面建立新的结构。恶性疟原虫的一个独特的致命方面是它在血细胞上产生表面突起（称为旋钮），使其粘附在血管系统的衬里上。这可以防止受感染的细胞被脾脏捕获和破坏，但也可以阻塞脑毛细血管，这是疟疾感染的主要死亡原因。一旦它们成熟，16-24个子寄生虫就会突破周围的空泡膜和红细胞膜（统称为出口）进入血液，在那里它们立即侵入新一轮的血细胞。入侵、粘附和外出的过程通过级联酶反应以及结构组分的表达和运输来调节。其中一些成分是疟疾特有的，使其成为未来药物开发的潜在目标。目前，它们中的大多数都很难描述。在这个项目中，我们专注于成熟的寄生虫突破两个边界膜进行出口的步骤。一系列高度调节的步骤导致寄生虫从血细胞中爆炸性释放。为了详细研究这些膜破裂事件，我们使用电子显微镜以纳米级分辨率对寄生虫发育后期受感染细胞的三维结构进行成像。这种成像与使用寄生虫突变体和药物样分子和酶抑制剂相结合，以在不同的出口步骤捕获寄生虫。这种方法已经使我们发现了一个新的，以前没有发现的出口的初始步骤。我们现在知道，这个过程始于寄生虫导致其液泡周围的膜变得渗漏。随后，这种膜被完全破坏，使寄生虫能够在血细胞内自由移动。不久之后，血细胞膜本身变得渗漏，然后最终细胞膜及其下面的细胞骨架破裂，使寄生虫逃逸并侵入新的宿主血细胞。随着基因编辑技术的最新进展，现在已经可以有条件地修改恶性疟原虫中的基因表达，我们将使用这种强大的技术来探测参与出口过程中步骤序列的关键疟疾组分的分子性质，功能和亚细胞定位。这些研究的结果可以为未来开发新的治疗方法奠定基础。

项目成果

Sequential roles for red blood cell binding proteins enable phased commitment to invasion for malaria parasites.

• DOI: 10.1038/s41467-023-40357-z
• 发表时间: 2023-08-01
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Hart, Melissa N.;Mohring, Franziska;DonVito, Sophia M.;Thomas, James A.;Mueller-Sienerth, Nicole;Wright, Gavin J.;Knuepfer, Ellen;Saibil, Helen R.;Moon, Robert W.
• 通讯作者: Moon, Robert W.

Sequential roles for red blood cell binding proteins enable phased commitment to invasion for malaria parasites

红细胞结合蛋白的连续作用使得疟疾寄生虫能够分阶段入侵

• DOI: 10.1101/2022.08.09.503398
• 发表时间: 2022
• 作者: Hart M

Peptidic boronic acids are potent cell-permeable inhibitors of the malaria parasite egress serine protease SUB1.

• DOI: 10.1073/pnas.2022696118
• 发表时间: 2021-05-18
• 期刊: Proceedings of the National Academy of Sciences of the United States of America
• 影响因子: 11.1
• 作者: Lidumniece E;Withers-Martinez C;Hackett F;Collins CR;Perrin AJ;Koussis K;Bisson C;Blackman MJ;Jirgensons A
• 通讯作者: Jirgensons A

Malaria Parasite Schizont Egress Antigen-1 Plays an Essential Role in Nuclear Segregation during Schizogony.

• DOI: 10.1128/mbio.03377-20
• 发表时间: 2021-03-09
• 期刊: mBio
• 影响因子: 6.4
• 作者: Perrin AJ;Bisson C;Faull PA;Renshaw MJ;Lees RA;Fleck RA;Saibil HR;Snijders AP;Baker DA;Blackman MJ
• 通讯作者: Blackman MJ