Biosyrdiesis of iron-sulfur proteins in Enlanoeba histotyrica

铁团簇在所有生物体中都很保守，在呼吸、电子传递、氧化还原和氮测试中发挥着关键作用。本研究旨在对溶组织内阿米巴铁硫生物合成的分子特征进行研究，了解其在寄生和致病中的作用。我们还旨在获得寄生虫体内半胱氨酸和丝氨酸生物合成的摩尔图。铁-硫的生物合成是由三个独立的途径中的一个或多个催化的：NIF、ISC和SUF，这取决于生物体。溶组素仅具有NIF途径的组成成分，即催化成分NIF和支架成分NifU。NIF系统在真核生物中的存在是前所未有的。我们发现，阿米巴NIF系统能够适应各种铁硫除尘器，在功能上取代了异源生物中ISC和SUF的功能，并且只在厌氧条件下起作用。我们还发现，NIF系统定位于细胞质，这与ISC和SUF形成鲜明对比，后者分别定位于线粒体和叶绿体。我们还发现，溶组乳杆菌有两条丝氨酸代谢途径，即磷酸化途径和非磷酸化途径，它们似乎分别参与了有助于糖异生的生物合成。在寄生原生生物中，这两条丝氨酸通路的存在是这种有机体独有的。这项研究有助于我们理解寄生生物中铁屑生物合成和丝氨酸/半胱氨酸代谢的生理意义。

Iron clusters are well conserved among all living organisms, and play a pivotal role in respiration, electron transport, redox, and nitrogen tetion. In this study, we aimed at molecular characterization of iron sulfur biosynthesis in Entamoeba histolytica, and understanding of its role in parasitism and pathogenesis. We also aimed at obtaining a Mole view of cysteine and serine biosynthesis in the parasite. Iron-sulfur biosynthesis is known to be catalyzed by one or more of three independent pathways : NIF, ISC, and SUF, depending upon organisms. E histolytica exclusively possesses components for the NIF pathway, namely the catalytic component NifS and the scaffold component NifU. The presence of the NIF system in eukaryotes is unprecedented. We showed that the amebic NIF system is capable of all kinds of iron sulfur dusters, functionally replace the function of ISC and SUF in a heterologous organism, and function only under anaerobic conditions. We also showed the NIF system is localized to the cytosol, which is in good contrast to ISC and SUF, localized to the mitochondria and chloroplast, respectively. We also showed that E. histolytica possesses two pathways for serine metabolism, namely phosphorylated and non-phosphorylated pathways, which seems to be involved in biosynthesis aid gluconeogenesis, respectively. The presence of both the serine pathways is unique to this organism among parasitic protists. The present study should help our understanding of physiological importance of iron duster biosynthesis and serine/cysteine metaboism in parasitic organisms.