HMA domain proteins as conserved targets of pathogens that exploit plasmodesmata

HMA 结构域蛋白作为利用胞间连丝的病原体的保守靶标

• 批准号: BB/X016056/1
• 负责人: Christine Faulkner
• 金额: $ 104万
• 依托单位: John Innes Centre
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FX016056%2F1
• 关键词: HMA; domain; proteins; conserved; targets

Microbial pathogens invade their hosts via a range of infection strategies that allow the pathogen to grow and reproduce. Infection can include physical processes that transform host cells and tissues to accommodate the invader, and molecular warfare in which proteins and small molecules are exchanged to impede and manipulate the other organism. At the molecular level, pathogens are armed with a repertoire of proteins and small molecules that can be delivered into host cells, targeting specific physiological processes to control cellular function. Microbial proteins that are delivered into host cells are referred to as effectors and while there are common themes amongst their function in targeting immune suppression and resource distribution, they have a wide variety of molecular targets, specific to a given microbe. Pathogen effectors from different kingdoms target host plasmodesmata, the cytoplasmic connections between cells. Plasmodesmata offer a pathway for some pathogens to pass between cells and spread through host tissues, as well as acting as conduits by which molecules can pass to sites where they are deployed in infection; effectors can pass from infected cells into uninfected cells and nutrients can pass freely from host sources to the site of infection. As might be expected, host cells usually try to close their plasmodesmata as a defence mechanism. However, several effectors that target plasmodesmata can prevent this response and maintain connectivity between host cells. Thus, plasmodesmata have emerged as a critical battleground between host and pathogen.There have been several observations of effectors from viral and fungal pathogens that target heavy metal associated (HMA) domain proteins located at plasmodesmata. That such diverse pathogens target the same class of proteins located at intercellular bridges suggests that HMA domain proteins offer significant gains during infection. Further, in many plant species HMA domains are integrated into immune receptor sequences where they act as decoys to bind the relevant effector and activate the immune receptor, triggering cell death and consequent resistance. Unfortunately, while immune receptor hijacking of effector-HMA domain interactions points to the significance of the association, it also impedes research into the role of the effector and the HMA target as it becomes masked by immune receptor activation.We recently showed that the Arabidopsis fungal pathogen Colletotrichum higginsianum produces an effector that targets a plasmodesmata-located HMA domain protein in the host. Arabidopsis does not produce immune receptors with integrated HMA domains, allowing us to investigate the role and mechanism of this interaction in infection. This will also allow us to ask how and why these effectors target plasmodesmata. As the C. higginsianum effector not only targets plasmodesmata but moves cell to cell and modifies plasmodesmata to allow large proteins to move between cells more frequently, it suggests that one effector function is to increase the capacity for molecular exchange between host cells.This proposal will use the Arabidopsis-Colletotrichum interaction to determine what function the effector and host target each play in infection. We will use structural biology to compare the interactions between the effector and target HMAs from diverse species and identify any conservation between the mechanisms by which this occurs. We will also exploit any conservation to determine if we can exchange the HMA domain in immune receptors from rice with the HMA domain from Arabidopsis targeted by Colletotrichum, and thus engineer an immune receptor that recognises the Colletotrichum effector and confers novel resistance.

微生物病原体通过一系列允许病原体生长和繁殖的感染策略入侵宿主。感染可以包括改变宿主细胞和组织以适应入侵者的物理过程，以及交换蛋白质和小分子以阻碍和操纵其他生物体的分子战争。在分子水平上，病原体配备了一系列蛋白质和小分子，可以将其传递到宿主细胞中，针对特定的生理过程来控制细胞功能。递送到宿主细胞中的微生物蛋白被称为效应子，虽然它们在靶向免疫抑制和资源分配方面的功能有共同的主题，但它们具有针对特定微生物的多种分子靶标。来自不同界的病原体效应子以宿主胞间连丝（细胞之间的细胞质连接）为目标。胞连丝为一些病原体提供了在细胞之间传递并通过宿主组织传播的途径，并充当分子可以传递到它们在感染中部署的部位的管道；效应子可以从受感染的细胞传递到未受感染的细胞，营养物质可以从宿主来源自由传递到感染部位。正如所预料的，宿主细胞通常会尝试关闭其胞间连丝作为防御机制。然而，一些针对胞间连丝的效应子可以阻止这种反应并维持宿主细胞之间的连接。因此，胞间连丝已成为宿主和病原体之间的关键战场。已经对来自病毒和真菌病原体的效应子进行了一些观察，这些效应子靶向位于胞间连丝的重金属相关（HMA）结构域蛋白。如此不同的病原体以位于细胞间桥的同一类蛋白质为目标，这表明 HMA 结构域蛋白在感染过程中提供了显着的收益。此外，在许多植物物种中，HMA 结构域被整合到免疫受体序列中，作为诱饵结合相关效应子并激活免疫受体，引发细胞死亡和随后的抵抗。不幸的是，虽然免疫受体劫持效应器-HMA结构域相互作用表明了这种关联的重要性，但它也阻碍了对效应器和HMA靶点作用的研究，因为它被免疫受体激活所掩盖。我们最近表明，拟南芥真菌病原体希金斯炭疽病菌 (Colletotrichum higginsianum) 产生一种效应子，该效应子以宿主体内胞间连丝定位的 HMA 结构域蛋白为目标。拟南芥不产生具有整合的 HMA 结构域的免疫受体，这使我们能够研究这种相互作用在感染中的作用和机制。这也将使我们能够询问这些效应器如何以及为何针对胞间连丝。由于 C. higginsianum 效应子不仅靶向胞间连丝，而且在细胞之间移动并修饰胞间连丝，使大蛋白更频繁地在细胞之间移动，这表明效应子功能之一是增加宿主细胞之间分子交换的能力。该提议将利用拟南芥-炭疽菌相互作用来确定效应子和宿主各自在感染中发挥的作用。我们将使用结构生物学来比较来自不同物种的效应子和目标 HMA 之间的相互作用，并确定发生这种情况的机制之间的任何保守性。我们还将利用任何保守性来确定是否可以将水稻免疫受体中的 HMA 结构域与炭疽菌靶向的拟南芥中的 HMA 结构域进行交换，从而设计出识别炭疽菌效应子并赋予新的抗性的免疫受体。