The mitochondrial peroxiredoxin displays distinct roles in different developmental stages of African trypanosomes
The mitochondrial peroxiredoxin displays distinct roles in different developmental stages of African trypanosomes
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DOI：
10.1016/j.redox.2020.101547
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发表时间：
2020-07-01
期刊：
影响因子：
11.4
通讯作者：
Krauth-Siegel, R. Luise
中科院分区：
文献类型：
--
作者：
Bogacz, Marta;Dirdjaja, Natalie;Krauth-Siegel, R. Luise
非洲锥虫体内的过氧化氢还原依赖于2-半胱氨酸过氧化物酶(Prxs)和谷胱甘肽过氧化物酶(Pxs)，这两种酶都是从色氨硫酮/色氨酸对获得其还原等价物，从而起到色氨酸过氧化物酶的作用。虽然胞浆形式的过氧化物酶是必不可少的，但线粒体mPrx和Px III在布鲁氏锥虫的血流中似乎是必不可少的。这导致人们认为，在这个以线粒体缺乏活性呼吸链为特征的发育阶段，可能只需要两种过氧化物酶中的一种。在这里，我们显示了在RNA干扰下Px III基因缺失和mPrx下调的血液细胞像亲本细胞一样增殖，这表明这两种线粒体过氧化物酶都是必不可少的。然而，当我们将培养温度提高到39摄氏度时，mPrx耗尽的细胞死亡，这表明在模拟哺乳动物宿主发烧的条件下，蛋白质变得必不可少。相反，在没有任何胁迫的情况下，在27摄氏度的标准条件下，昆虫阶段原环毛虫mPrx的耗尽会导致增殖缺陷。在缺少mPrx的情况下，表达在线粒体基质中的色氨酸还原蛋白偶联的roGFP2生物传感器不能对抗霉素A处理产生反应。因此，mPrx通过产生台盼硫二硫化物减少线粒体过氧化氢，并作为过氧化物酶发挥作用。然而，mPrx缺失的原环状细胞既没有表现出胞浆或线粒体的氧化还原状态的任何变化，也没有增加对外部氧化应激源的敏感性，这表明过氧化物酶活性不是关键的生理功能。在mPrx耗尽后，细胞几乎停止增殖，呈高度拉长的形状，MitoTracker Red染色减弱。与哺乳动物血液中布氏锥虫和利什曼原虫的情况不同，mPrx似乎对非洲锥虫昆虫阶段的形态、线粒体功能和增殖起着结构性作用。
Hydroperoxide reduction in African trypanosomes relies on 2-Cys-peroxiredoxins (Prxs) and glutathione peroxidase-type enzymes (Pxs) which both obtain their reducing equivalents from the trypanothione/tryparedoxin couple and thus act as tryparedoxin peroxidases. While the cytosolic forms of the peroxidases are essential, the mitochondrial mPrx and Px III appear dispensable in bloodstream Trypanosoma brucei. This led to the suggestion that in this developmental stage which is characterized by a mitochondrion that lacks an active respiratory chain, only one of the two peroxidases might be required. Here we show that bloodstream cells in which the Px III gene is deleted and mPrx is down-regulated by RNA interference, proliferate as the parental cells indicating that both mitochondrial peroxidases are dispensable. However, when we raised the culture temperature to 39 degrees C, mPrx-depleted cells died indicating that under conditions mimicking a fever situation in the mammalian host, the protein becomes essential. In contrast, depletion of mPrx in insect stage procyclic T. brucei causes a proliferation defect under standard conditions at 27 degrees C, in the absence of any stress. In the absence of mPrx, a tryparedoxin-coupled roGFP2 biosensor expressed in the mitochondrial matrix is unable to respond to antimycin A treatment. Thus mPrx reduces mitochondrial H2O2 with the generation of trypanothione disulfide and acts as peroxidase. However, mPrx-depleted procyclic cells neither display any alteration in the cytosolic or mitochondrial trypanothione redox state nor increased sensitivity towards exogenous oxidative stressors suggesting that the peroxidase activity is not the crucial physiological function. After prolonged mPrx-depletion, the cells almost stop proliferation and display a highly elongated shape and diminished MitoTracker Red staining. In contrast to the situation in the mammalian bloodstream T. brucei and Leishmania, mPrx appears to play a constitutive role for the morphology, mitochondrial function and proliferation of the insect stage of African trypanosomes.