Identification of Plant-like Galactolipids in Chromera velia, a Photosynthetic Relative of Malaria Parasites
Identification of Plant-like Galactolipids in Chromera velia, a Photosynthetic Relative of Malaria Parasites
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DOI：
10.1074/jbc.m111.254979
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发表时间：
2011-08-26
影响因子：
4.8
通讯作者：
McFadden, Geoffrey I.
中科院分区：
文献类型：
--
作者：
Botte, Cyrille Y.;Yamaryo-Botte, Yoshiki;McFadden, Geoffrey I.
顶复门是原生生物寄生虫，包括疟原虫属，疟疾的病原体，以及引起弓形虫病的弓形虫。大多数顶复门都有一个残余质体，即顶质体，它是通过一种红色的内共生体的次生内共生获得的。尽管是非光合作用，顶质体在其他方面代谢类似于藻类和植物质体，是寄生虫生存所必需的。以往的研究表明，弓形虫的膜脂具有质体半乳糖脂的一些结构特征，质体半乳糖脂是主要的质体脂类。然而，直接证据的植物样酶负责半乳糖脂合成Apicomplexan寄生虫尚未获得。Chromera velia是最近在澳大利亚珊瑚中发现的顶复门亲戚。C. velia保留了一个光合质体，提供了一个独特的模式来研究顶质体的进化。在这里，我们报告明确存在植物样的单半乳糖基甘油二酯和双半乳糖基甘油二酯在C。膜和定位二半乳糖基甘油二酯的质体。我们还提供了植物样的生物合成途径的证据，并确定负责半乳糖脂合成的候选半乳糖基转移酶。我们的研究为含质体真核生物中这些重要酶的进化提供了新的见解，并将有助于重建疟原虫和弓形虫等重要寄生虫中甘油脂代谢的进化。
Apicomplexa are protist parasites that include Plasmodium spp., the causative agents of malaria, and Toxoplasma gondii, responsible for toxoplasmosis. Most Apicomplexa possess a relict plastid, the apicoplast, which was acquired by secondary endosymbiosis of a red alga. Despite being nonphotosynthetic, the apicoplast is otherwise metabolically similar to algal and plant plastids and is essential for parasite survival. Previous studies of Toxoplasma gondii identified membrane lipids with some structural features of plastid galactolipids, the major plastid lipid class. However, direct evidence for the plant-like enzymes responsible for galactolipid synthesis in Apicomplexan parasites has not been obtained. Chromera velia is an Apicomplexan relative recently discovered in Australian corals. C. velia retains a photosynthetic plastid, providing a unique model to study the evolution of the apicoplast. Here, we report the unambiguous presence of plant-like monogalactosyldiacylglycerol and digalactosyldiacylglycerol in C. velia and localize digalactosyldiacylglycerol to the plastid. We also provide evidence for a plant-like biosynthesis pathway and identify candidate galactosyltran-ferases responsible for galactolipid synthesis. Our study provides new insights in the evolution of these important enzymes in plastid-containing eukaryotes and will help reconstruct the evolution of glycerolipid metabolism in important parasites such as Plasmodium and Toxoplasma.