Trypanosomatids regulate gene expression mainly at the post‐transcriptional level through processing, exporting and stabilising mRNA and control of translation. In most eukaryotes, protein synthesis is regulated by phosphorylation of eukaryotic initiation factor 2 (eIF2) at serine 51. Phosphorylation halts overall translation by decreasing availability of initiator tRNA^met to form translating ribosomes. In trypanosomatids, the N‐terminus of eIF2α is extended with threonine 169 the homologous phosphorylated residue. Here, we evaluated whether eIF2α phosphorylation varies during the Trypanosoma cruzi life cycle, the etiological agent of Chagas' disease. Total levels of eIF2α are diminished in infective and non‐replicative trypomastigotes compared with proliferative forms from the intestine of the insect vector or amastigotes from mammalian cells, consistent with decreased protein synthesis reported in infective forms. eIF2α phosphorylation increases in proliferative intracellular forms prior to differentiation into trypomastigotes. Parasites overexpressing eIF2α^T169A or with an endogenous CRISPR/Cas9‐generated eIF2α^T169A mutation were created and analysis revealed alterations to the proteome, largely unrelated to the presence of μORF in epimastigotes. eIF2α^T169A mutant parasites produced fewer trypomastigotes with lower infectivity than wild type, with increased levels of sialylated mucins and oligomannose glycoproteins, and decreased galactofuranose epitopes and the surface protease GP63 on the cell surface. We conclude that eIF2α expression and phosphorylation levels affect proteins relevant for intracellular progression of T. cruzi.

中文翻译：

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EIF2α 磷酸化在细胞内无鞭毛体中受到调节，以产生感染性克氏锥虫锥体鞭毛体形式。

锥虫主要在转录后水平通过加工、输出和稳定 mRNA 以及控制翻译来调节基因表达。^{在大多数真核生物中，蛋白质合成受真核起始因子 2 (eIF2) 在丝氨酸 51 的磷酸化调节。磷酸化通过}降低起始 tRNA 的可用性来停止整体翻译，从而形成翻译核糖体。在锥虫中，eIF2α 的N末端用苏氨酸 169 （同源磷酸化残基）延伸。在这里，我们评估了在克氏锥虫期间 eIF2α 磷酸化是否发生变化生命周期，恰加斯病的病原体。与来自昆虫载体肠道的增殖形式或来自哺乳动物细胞的无鞭毛体相比，感染性和非复制性锥体中的 eIF2α 总水平降低，这与感染性形式中报道的蛋白质合成减少一致。在分化为锥体鞭毛体之前，eIF2α 磷酸化在增殖性细胞内形式中增加。产生过表达 eIF2α ^T169A或具有内源性 CRISPR/Cas9 产生的 eIF2α ^T169A突变的寄生虫，分析揭示了蛋白质组的改变，这在很大程度上与外鞭毛体中 μORF 的存在无关。^eIF2α T169A与野生型相比，突变型寄生虫产生的锥鞭毛体较少，感染性较低，唾液酸化粘蛋白和寡甘露糖糖蛋白水平增加，细胞表面的呋喃半乳糖表位和表面蛋白酶 GP63 减少。我们得出结论，eIF2α 表达和磷酸化水平影响与T. cruzi细胞内进展相关的蛋白质。