Sphingolipid synthesis and scavenging in the intracellular apicomplexan parasite, Toxoplasma gondii.
Sphingolipid synthesis and scavenging in the intracellular apicomplexan parasite, Toxoplasma gondii.
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DOI：
10.1016/j.molbiopara.2012.11.007
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发表时间：
2013-01
影响因子：
1.5
通讯作者：
Denny, Paul W.
中科院分区：
文献类型：
--
作者：
Pratt, Steven;Wansadhipathi-Kannangara, Nilu K.;Bruce, Catherine R.;Mina, John G.;Shams-Eldin, Hosam;Casas, Josefina;Hanada, Kentaro;Schwarz, Ralph T.;Sonda, Sabrina;Denny, Paul W.
弓形虫鞘脂合酶（TgSLS）的鉴定和表征。TgSLS肌醇磷酸神经酰胺合酶活性的证明。弓形虫提取物中肌醇磷酸神经酰胺的鉴定。宿主鞘脂生物合成在弓形虫增殖中的作用。宿主生物合成对增殖不是必需的，从头合成可能是关键。鞘脂是真核细胞膜，特别是质膜的重要组成部分，并参与多种信号转导途径。哺乳动物产生鞘磷脂（SM）作为主要的复合鞘脂通过充分表征SM合酶。相反，酵母、植物和一些原生动物利用进化上相关的肌醇磷酸神经酰胺（IPC）合酶来合成IPC。这种活性在哺乳动物中没有等同物，IPC合酶已被提议作为抗真菌和抗原生动物的靶标。然而，缺乏对顶复门原生动物寄生虫的鞘脂生物合成途径的详细了解。在这项研究中，生物信息学分析表明，一个单拷贝的直向同源物的假定SM合酶从apicomplexan恶性疟原虫（疟疾的病原体）是一个真正的鞘脂合酶在相关的模式寄生虫，弓形虫（TgSLS）。随后，通过突变细胞系的互补，TgSLS被指示为酵母IPC合酶（AUR1p）的功能性直向同源物，证明了对充分表征的AUR1p抑制剂aureobasidin A的抗性。在体外，重组TgSLS表现出IPC合酶活性，并且首次在T.弓形虫脂质提取物的质谱分析。此外，宿主鞘脂的生物合成被证明影响，但不是必需的，T。弓形虫增殖，这表明，虽然清除确实发生从头鞘脂合成可能是重要的寄生。
► Identification and characterisation of Toxoplasma sphingolipid synthase (TgSLS). ► Demonstration of TgSLS inositol phosphorylceramide synthase activity. ► Identification of inositol phosphorylceramide in Toxoplasma extracts. ► Delineation of role of host sphingolipid biosynthesis in Toxoplasma proliferation. ► Host biosynthesis non-essential for proliferation, de novo synthesis could be key. Sphingolipids are essential components of eukaryotic cell membranes, particularly the plasma membrane, and are involved in a diverse array of signal transduction pathways. Mammals produce sphingomyelin (SM) as the primary complex sphingolipid via the well characterised SM synthase. In contrast yeast, plants and some protozoa utilise an evolutionarily related inositol phosphorylceramide (IPC) synthase to synthesise IPC. This activity has no mammalian equivalent and IPC synthase has been proposed as a target for anti-fungals and anti-protozoals. However, detailed knowledge of the sphingolipid biosynthetic pathway of the apicomplexan protozoan parasites was lacking. In this study bioinformatic analyses indicated a single copy orthologue of the putative SM synthase from the apicomplexan Plasmodium falciparum (the causative agent of malaria) was a bona fide sphingolipid synthase in the related model parasite, Toxoplasma gondii (TgSLS). Subsequently, TgSLS was indicated, by complementation of a mutant cell line, to be a functional orthologue of the yeast IPC synthase (AUR1p), demonstrating resistance to the well characterised AUR1p inhibitor aureobasidin A. In vitro, recombinant TgSLS exhibited IPC synthase activity and, for the first time, the presence of IPC was demonstrated in T. gondii lipid extracts by mass spectrometry. Furthermore, host sphingolipid biosynthesis was indicated to influence, but be non-essential for, T. gondii proliferation, suggesting that whilst scavenging does take place de novo sphingolipid synthesis may be important for parasitism.
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影响因子：
6.7
作者：
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