The Phytophthora infestans Haustorium Is a Site for Secretion of Diverse Classes of Infection-Associated Proteins.
The Phytophthora infestans Haustorium Is a Site for Secretion of Diverse Classes of Infection-Associated Proteins.
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DOI：
10.1128/mbio.01216-18
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发表时间：
2018-08-28
期刊：
影响因子：
6.4
通讯作者：
Birch PRJ
中科院分区：
文献类型：
--
作者：
Wang S;Welsh L;Thorpe P;Whisson SC;Boevink PC;Birch PRJ
致病疫霉分泌的许多不同种类的蛋白质可能影响或促进感染。阐明它们在感染过程中的分泌位置和方式是开发控制其递送过程的方法的重要一步。我们使用了一种抑制剂的传统分泌，以确定以下不同类别的感染相关的胞外蛋白：细胞壁降解和细胞壁修饰酶，微生物相关的分子模式样蛋白，可能会引起免疫反应，和预测抑制免疫的质外体效应。相反，易位到宿主细胞中的细胞质效应物的分泌是非常规的，因为它对抑制剂处理不敏感。这一证据进一步支持了以下发现：致病疫霉差异分泌在质外体中有活性的蛋白质和在宿主细胞质中有活性的效应蛋白。重要的是，它表明，疾病特异性的发育结构，吸器，是一个主要的分泌位点，在感染过程中的不同蛋白质类。卵菌马铃薯枯萎病病原体致病疫霉（Phytophthora infestans）分泌多种蛋白质以操纵宿主植物免疫。然而，关于它们在感染期间如何以及在何处分泌的知识有限。在这里，我们使用内质网（ER）到高尔基体分泌途径抑制剂布雷菲德菌素A（BFA）与液相色谱-电喷雾串联质谱（LC-MS/MS）相结合，以确定从致病疫霉细胞外蛋白，通常分泌从体外培养的菌丝。我们确定了19种蛋白质与预测的信号肽，可能会影响植物的相互作用，其中分泌被BFA减弱。除了抑制的质外体效应EPIC 1，半胱氨酸蛋白酶抑制剂，我们表明，分泌的细胞壁降解果胶酯酶PE 1和微生物相关的分子模式（MAMP）样激发素INF 4被抑制在体外和植物中的BFA，表明这些蛋白质是由传统的，高尔基体介导的途径分泌。相比之下，BFA不抑制细胞质RXLR（Arg-[任何氨基酸]-Leu-Arg）效应子Pi 22926的分泌。在感染期间，INF 4在植物细胞外积累，而RXLR效应子Pi 22926进入植物细胞并在细胞核中积累。致病疫霉效应子、PE 1酶和INF 4都是从吸器分泌的，吸器是穿透植物细胞壁与宿主质膜形成密切相互作用的病原体结构。我们的研究结果表明吸器是一个主要网站的传统和非传统分泌的蛋白质具有不同的功能在感染过程中。
There are many different classes of proteins secreted from Phytophthora infestans that may influence or facilitate infection. Elucidating where and how they are secreted during infection is an important step toward developing methods to control their delivery processes. We used an inhibitor of conventional secretion to identify the following different classes of infection-associated extracellular proteins: cell wall-degrading and cell wall-modifying enzymes, microbe-associated molecular pattern-like proteins that may elicit immune responses, and apoplastic effectors that are predicted to suppress immunity. In contrast, secretion of a cytoplasmic effector that is translocated into host cells is nonconventional, as it is insensitive to inhibitor treatment. This evidence further supports the finding that proteins that are active in the apoplast and effector proteins that are active in the host cytoplasm are differentially secreted by P. infestans. Critically, it demonstrates that a disease-specific developmental structure, the haustorium, is a major secretion site for diverse protein classes during infection. The oomycete potato blight pathogen Phytophthora infestans secretes a diverse set of proteins to manipulate host plant immunity. However, there is limited knowledge about how and where they are secreted during infection. Here we used the endoplasmic reticulum (ER)-to-Golgi secretion pathway inhibitor brefeldin A (BFA) in combination with liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) to identify extracellular proteins from P. infestans that were conventionally secreted from in vitro-cultured hyphae. We identified 19 proteins with predicted signal peptides that potentially influence plant interactions for which secretion was attenuated by BFA. In addition to inhibition by the apoplastic effector EPIC1, a cysteine protease inhibitor, we show that secretion of the cell wall-degrading pectinesterase enzyme PE1 and the microbe-associated molecular pattern (MAMP)-like elicitin INF4 was inhibited by BFA in vitro and in planta, demonstrating that these proteins are secreted by the conventional, Golgi-mediated pathway. For comparison, secretion of a cytoplasmic RXLR (Arg-[any amino acid]-Leu-Arg) effector, Pi22926, was not inhibited by BFA. During infection, whereas INF4 accumulated outside the plant cell, RXLR effector Pi22926 entered the plant cell and accumulated in the nucleus. The P. infestans effectors, the PE1 enzyme, and INF4 were all secreted from haustoria, pathogen structures that penetrate the plant cell wall to form an intimate interaction with the host plasma membrane. Our findings show the haustorium to be a major site of both conventional and nonconventional secretion of proteins with diverse functions during infection.