Department of Molecular Microbiology, Ruth and Bruce Rappaport Faculty of Medicine, Technion, Haifa Israel.
Department of Parasitology, Graduate School of Medicine, Gunma University, Showa-machi, Maebashi, Gunma, Japan.
PLoS Pathog. 2018 Oct 11;14(10):e1007295. doi: 10.1371/journal.ppat.1007295. eCollection 2018 Oct.
Amebiasis, a global intestinal parasitic disease, is due to Entamoeba histolytica. This parasite, which feeds on bacteria in the large intestine of its human host, can trigger a strong inflammatory response upon invasion of the colonic mucosa. Whereas information about the mechanisms which are used by the parasite to cope with oxidative and nitrosative stresses during infection is available, knowledge about the contribution of bacteria to these mechanisms is lacking. In a recent study, we demonstrated that enteropathogenic Escherichia coli O55 protects E. histolytica against oxidative stress. Resin-assisted capture (RAC) of oxidized (OX) proteins coupled to mass spectrometry (OX-RAC) was used to investigate the oxidation status of cysteine residues in proteins present in E. histolytica trophozoites incubated with live or heat-killed E. coli O55 and then exposed to H2O2-mediated oxidative stress. We found that the redox proteome of E. histolytica exposed to heat-killed E. coli O55 is enriched with proteins involved in redox homeostasis, lipid metabolism, small molecule metabolism, carbohydrate derivative metabolism, and organonitrogen compound biosynthesis. In contrast, we found that proteins associated with redox homeostasis were the only OX-proteins that were enriched in E. histolytica trophozoites which were incubated with live E. coli O55. These data indicate that E. coli has a profound impact on the redox proteome of E. histolytica. Unexpectedly, some E. coli proteins were also co-identified with E. histolytica proteins by OX-RAC. We demonstrated that one of these proteins, E. coli malate dehydrogenase (EcMDH) and its product, oxaloacetate, are key elements of E. coli-mediated resistance of E. histolytica to oxidative stress and that oxaloacetate helps the parasite survive in the large intestine. We also provide evidence that the protective effect of oxaloacetate against oxidative stress extends to Caenorhabditis elegans.
阿米巴病是一种全球性的肠道寄生虫病，由溶组织内阿米巴原虫引起。这种寄生虫以其人类宿主大肠内的细菌为食，在侵入结肠黏膜时会引发强烈的炎症反应。虽然有关寄生虫在感染过程中应对氧化应激和硝化应激的机制的信息已经有了，但对于细菌对这些机制的贡献的了解还很缺乏。在最近的一项研究中，我们证明了致病性大肠杆菌 O55 可以保护溶组织内阿米巴原虫免受氧化应激的影响。使用氧化蛋白树脂辅助捕获（OX-RAC）结合质谱技术（OX-RAC）来研究在与活的或热杀死的大肠杆菌 O55 孵育后暴露于 H2O2 介导的氧化应激的溶组织内阿米巴原虫滋养体中存在的蛋白质的半胱氨酸残基的氧化状态。我们发现，暴露于热杀死的大肠杆菌 O55 的溶组织内阿米巴原虫的氧化还原蛋白质组富含参与氧化还原稳态、脂类代谢、小分子代谢、碳水化合物衍生物代谢和有机含氮化合物生物合成的蛋白质。相比之下，我们发现与氧化还原稳态相关的蛋白质是在与活的大肠杆菌 O55 孵育的溶组织内阿米巴原虫滋养体中唯一富集的 OX-蛋白质。这些数据表明，大肠杆菌对溶组织内阿米巴原虫的氧化还原蛋白质组有深远的影响。出乎意料的是，一些大肠杆菌蛋白质也通过 OX-RAC 与溶组织内阿米巴原虫蛋白质共同鉴定。我们证明，这些蛋白质中的一种，即大肠杆菌苹果酸脱氢酶（EcMDH）及其产物草酰乙酸，是大肠杆菌介导的溶组织内阿米巴原虫对氧化应激抗性的关键因素，并且草酰乙酸有助于寄生虫在大肠中生存。我们还提供了证据表明草酰乙酸对氧化应激的保护作用扩展到秀丽隐杆线虫。
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