Typical two-cysteine peroxiredoxins (2-Cys-PRXs) are HO-metabolizing enzymes whose activity relies on two cysteine residues. Protists of the family invariably express one cytosolic 2-Cys-PRX (cPRX1). However, the sub-family features an additional isoform (cPRX2), almost identical to cPRX1, except for the lack of an elongated C-terminus with a Tyr-Phe (YF) motif. Previously, cytosolic PRXs were considered vital components of the trypanosomatid antioxidant machinery. Here, we shed new light on the properties, functions and relevance of cPRXs from the human pathogen . We show first that cPRX1 is sensitive to inactivation by hyperoxidation, mirroring other YF-containing PRXs participating in redox signaling. Using genetic fusion constructs with roGFP2, we establish that cPRX1 and cPRX2 can act as sensors for HO and oxidize protein thiols with implications for signal transduction. Third, we show that while disrupting the cPRX-encoding genes increases susceptibility of promastigotes to external HO, both enzymes are dispensable for the parasites to endure the macrophage respiratory burst, differentiate into amastigotes and initiate infections. This study introduces a novel perspective on the functions of trypanosomatid cPRXs, exposing their dual roles as both peroxidases and redox sensors. Furthermore, the discovery that can adapt to the absence of both enzymes has significant implications for our understanding of infections and their treatment. Importantly, it questions the conventional notion that the oxidative response of macrophages during phagocytosis is a major barrier to infection and the suitability of cPRXs as drug targets for leishmaniasis.

中文翻译：

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胞质超氧化敏感且稳健的利什曼原虫过氧化还原蛋白 cPRX1 和 cPRX2 对于寄生虫感染来说都是可有可无的

典型的二半胱氨酸过氧化还原蛋白 (2-Cys-PRX) 是 H2O 代谢酶，其活性依赖于两个半胱氨酸残基。该家族的原生生物总是表达一种胞质 2-Cys-PRX (cPRX1)。然而，该亚家族具有一个额外的亚型 (cPRX2)，除了缺少带有 Tyr-Phe (YF) 基序的延长的 C 末端外，几乎与 cPRX1 相同。此前，胞质 PRX 被认为是锥虫抗氧化机制的重要组成部分。在这里，我们对人类病原体 cPRX 的特性、功能和相关性有了新的认识。我们首先证明 cPRX1 对过度氧化导致的失活敏感，这反映了参与氧化还原信号传导的其他含 YF 的 PRX。使用 roGFP2 的基因融合构建体，我们确定 cPRX1 和 cPRX2 可以充当 H2O 的传感器并氧化蛋白质硫醇，从而对信号转导产生影响。第三，我们发现，虽然破坏 cPRX 编码基因会增加前鞭毛体对外部 H2O 的敏感性，但这两种酶对于寄生虫忍受巨噬细胞呼吸爆发、分化为无鞭毛体并引发感染来说都是可有可无的。这项研究介绍了锥虫 cPRX 功能的新视角，揭示了它们作为过氧化物酶和氧化还原传感器的双重作用。此外，能够适应两种酶缺失的发现对于我们对感染及其治疗的理解具有重要意义。重要的是，它质疑了传统观念，即吞噬过程中巨噬细胞的氧化反应是感染的主要障碍，以及 cPRX 作为利什曼病药物靶点的适用性。