The adaptation of eukaryotic cells to anaerobic conditions is reflected by substantial changes to mitochondrial metabolism and functional reduction. Hydrogenosomes belong among the most modified mitochondrial derivative and generate molecular hydrogen concomitant with ATP synthesis. The reduction of mitochondria is frequently associated with loss of peroxisomes, which compartmentalize pathways that generate reactive oxygen species (ROS) and thus protect against cellular damage. The biogenesis and function of peroxisomes are tightly coupled with mitochondria. These organelles share fission machinery components, oxidative metabolism pathways, ROS scavenging activities, and some metabolites. The loss of peroxisomes in eukaryotes with reduced mitochondria is thus not unexpected. Surprisingly, we identified peroxisomes in the anaerobic, hydrogenosome-bearing protist Mastigamoeba balamuthi We found a conserved set of peroxin (Pex) proteins that are required for protein import, peroxisomal growth, and division. Key membrane-associated Pexs (MbPex3, MbPex11, and MbPex14) were visualized in numerous vesicles distinct from hydrogenosomes, the endoplasmic reticulum (ER), and Golgi complex. Proteomic analysis of cellular fractions and prediction of peroxisomal targeting signals (PTS1/PTS2) identified 51 putative peroxisomal matrix proteins. Expression of selected proteins in Saccharomyces cerevisiae revealed specific targeting to peroxisomes. The matrix proteins identified included components of acyl-CoA and carbohydrate metabolism and pyrimidine and CoA biosynthesis, whereas no components related to either β-oxidation or catalase were present. In conclusion, we identified a subclass of peroxisomes, named "anaerobic" peroxisomes that shift the current paradigm and turn attention to the reductive evolution of peroxisomes in anaerobic organisms.

中文翻译：

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Mastigamoeba balamuthi 中的厌氧过氧化物酶体。


真核细胞对厌氧条件的适应表现为线粒体代谢的显着变化和功能降低。氢酶体属于修饰最多的线粒体衍生物之一，在 ATP 合成的同时产生分子氢。线粒体的减少通常与过氧化物酶体的损失有关，过氧化物酶体将产生活性氧（ROS）的途径区分开来，从而防止细胞损伤。过氧化物酶体的生物发生和功能与线粒体紧密耦合。这些细胞器共享裂变机制组件、氧化代谢途径、ROS 清除活性和一些代谢物。因此，线粒体减少的真核生物中过氧化物酶体的损失并不意外。令人惊讶的是，我们在厌氧、携带氢酶体的原生生物 Mastigamoeba balamuthi 中鉴定出了过氧化物酶体。我们发现了一组保守的过氧化物酶 (Pex) 蛋白，它们是蛋白质输入、过氧化物酶体生长和分裂所需的。关键的膜相关 Pex（MbPex3、MbPex11 和 MbPex14）在许多不同于氢糖体、内质网 (ER) 和高尔基复合体的囊泡中可见。细胞组分的蛋白质组学分析和过氧化物酶体靶向信号 (PTS1/PTS2) 的预测鉴定出 51 种假定的过氧化物酶体基质蛋白。酿酒酵母中选定蛋白质的表达揭示了对过氧化物酶体的特异性靶向。鉴定出的基质蛋白包括酰基辅酶A和碳水化合物代谢以及嘧啶和辅酶A生物合成的成分，而不存在与β-氧化或过氧化氢酶相关的成分。 总之，我们确定了过氧化物酶体的一个亚类，称为“厌氧”过氧化物酶体，它改变了当前的范式，并将注意力转向厌氧生物中过氧化物酶体的还原进化。