Evolutionary conservation and in vitro reconstitution of microsporidian iron-sulfur cluster biosynthesis
Evolutionary conservation and in vitro reconstitution of microsporidian iron-sulfur cluster biosynthesis
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DOI：
10.1038/ncomms13932
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发表时间：
2017-01-04
影响因子：
16.6
通讯作者：
Lill, Roland
中科院分区：
文献类型：
--
作者：
Freibert, Sven-A.;Goldberg, Alina V.;Lill, Roland
微孢子虫是专性的细胞内寄生虫，通过约化进化使其基因组含量和亚细胞结构最小化。在这里，我们证明了人鞭毛虫的线粒体(线粒体)是铁-硫簇(ISC)组装的功能部位，我们认为这是这些细胞器的基本任务。细胞分离、荧光成像和免疫电子显微镜显示，线粒体包含一条完整的[2Fe-2S]簇生物合成途径，我们用纯化的线粒体ISC蛋白进行了生化重组。人毛滴虫胞质铁硫蛋白组装(CIA)途径包括必需的Cfd1-Nbp35支架复合体，光谱分析表明，Cfd1-Nbp35支架复合体组装成[4Fe-4S]簇。系统发育分析表明，ISC和CIA途径以细菌为主，而胞质和核靶标Fe/S蛋白主要为古生菌。这种铁/S相关蛋白和途径的混合进化史，以及它们在高度减少的寄生虫中的强烈保守性，为真核生物的古代嵌合祖先提供了令人信服的证据。
Microsporidians are obligate intracellular parasites that have minimized their genome content and sub-cellular structures by reductive evolution. Here, we demonstrate that cristae-deficient mitochondria (mitosomes) of Trachipleistophora hominis are the functional site of iron-sulfur cluster (ISC) assembly, which we suggest is the essential task of these organelles. Cell fractionation, fluorescence imaging and immunoelectron microscopy demonstrate that mitosomes contain a complete pathway for [2Fe-2S] cluster biosynthesis that we biochemically reconstituted using purified mitosomal ISC proteins. The T. hominis cytosolic iron-sulfur protein assembly (CIA) pathway includes the essential Cfd1-Nbp35 scaffold complex that assembles a [4Fe-4S] cluster as shown by spectroscopic methods in vitro. Phylogenetic analyses reveal that the ISC and CIA pathways are predominantly bacterial, but their cytosolic and nuclear target Fe/S proteins are mainly archaeal. This mixed evolutionary history of Fe/S-related proteins and pathways, and their strong conservation among highly reduced parasites, provides compelling evidence for the ancient chimeric ancestry of eukaryotes.