Knock-downs of iron-sulfur cluster assembly proteins IscS and IscU down-regulate the active mitochondrion of procyclic Trypanosoma brucei
Knock-downs of iron-sulfur cluster assembly proteins IscS and IscU down-regulate the active mitochondrion of procyclic Trypanosoma brucei
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DOI：
10.1074/jbc.m513781200
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发表时间：
2006-09-29
影响因子：
4.8
通讯作者：
Tachezy, Jan
中科院分区：
文献类型：
--
作者：
Smid, Ondrej;Horakova, Eva;Tachezy, Jan
转化的代谢下调的哺乳动物血流阶段的布氏锥虫的ATP生产的昆虫前循环阶段的代谢，伴随着从头合成的柠檬酸循环酶和呼吸链的组成部分。由于这些代谢途径包含多种铁硫（FeS）蛋白，因此需要它们的合成，包括形成FeS簇。然而，我们对锥虫中FeS簇的生物合成一无所知，锥虫是与酵母和人类在进化上相距甚远的生物。在这里，我们证明了两个线粒体蛋白，半胱氨酸脱硫酶TbiscS和金属伴侣TbiscU，锥虫和这种寄生虫的功能保守。敲低的TbiscS和TbiscU在procyclic阶段通过RNA干扰导致的标志物FeS酶乌头酸酶的活性降低，因为缺乏FeS簇在细胞质和细胞质中。此外，下调TbiscS和TbiscU影响了前环T的代谢。布鲁氏杆菌，使他们的线粒体类似于细胞器的血流阶段;线粒体ATP的生产受损，呼吸链蛋白复合物泛喹啉-细胞色素-c还原酶的活性降低，丙酮酸的生产作为葡萄糖代谢的最终产物增强。这些结果表明，线粒体FeS簇组装是必不可少的完成T。布鲁氏菌生活史
Transformation of the metabolically down-regulated mitochondrion of the mammalian bloodstream stage of Trypanosoma brucei to the ATP-producing mitochondrion of the insect procyclic stage is accompanied by the de novo synthesis of citric acid cycle enzymes and components of the respiratory chain. Because these metabolic pathways contain multiple iron-sulfur (FeS) proteins, their synthesis, including the formation of FeS clusters, is required. However, nothing is known about FeS cluster biogenesis in trypanosomes, organisms that are evolutionarily distant from yeast and humans. Here we demonstrate that two mitochondrial proteins, the cysteine desulfurase TbiscS and the metallochaperone TbiscU, are functionally conserved in trypanosomes and essential for this parasite. Knock-downs of TbiscS and TbiscU in the procyclic stage by means of RNA interference resulted in reduced activity of the marker FeS enzyme aconitase in both the mitochondrion and cytosol because of the lack of FeS clusters. Moreover, down-regulation of TbiscS and TbiscU affected the metabolism of procyclic T. brucei so that their mitochondria resembled the organelle of the bloodstream stage; mitochondrial ATP production was impaired, the activity of the respiratory chain protein complex ubiquinol-cytochrome-c reductase was reduced, and the production of pyruvate as an end product of glucose metabolism was enhanced. These results indicate that mitochondrial FeS cluster assembly is indispensable for completion of the T. brucei life cycle.