PDF(Pubmed)
Abstract：
Typical two-cysteine peroxiredoxins (2-Cys-PRXs) are H2O2-metabolizing enzymes whose activity relies on two cysteine residues. Protists of the family Trypanosomatidae invariably express one cytosolic 2-Cys-PRX (cPRX1). However, the Leishmaniinae 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 Leishmania infantum. We show first that LicPRX1 is sensitive to inactivation by hyperoxidation, mirroring other YF-containing PRXs participating in redox signaling. Using genetic fusion constructs with roGFP2, we establish that LicPRX1 and LicPRX2 can act as sensors for H2O2 and oxidize protein thiols with implications for signal transduction. Third, we show that while disrupting the LicPRX-encoding genes increases susceptibility of L. infantum promastigotes to external H2O2in vitro, both enzymes are dispensable for the parasites to endure the macrophage respiratory burst, differentiate into amastigotes and initiate in vivo 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 Leishmania can adapt to the absence of both enzymes has significant implications for our understanding of Leishmania 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.
摘要：
典型的双半胱氨酸过氧化物酶(2-Cys-PRX)是H2O2代谢酶,其活性依赖于两个半胱氨酸残基。锥虫科的原生生物总是表达一种胞质2-Cys-PRX（cPRX1）。然而,利什曼科亚科具有额外的同工型(cPRX2)，几乎与cPRX1相同，除了缺少带有Tyr-Phe（YF）基序的细长C末端。以前,胞质PRX被认为是锥虫虫抗氧化机制的重要组成部分。这里,我们对房产有了新的认识，来自人类病原体婴儿利什曼原虫的cPRX的功能和相关性。我们首先证明LicPRX1对过氧化失活敏感，反映参与氧化还原信号传导的其他含YF的PRX。使用具有roGFP2的遗传融合构建体，我们确定LicPRX1和LicPRX2可以充当H2O2的传感器，并氧化蛋白质硫醇，这对信号转导有影响。第三，我们表明，虽然破坏LicPRX编码基因会增加婴儿前鞭毛虫对体外H2O2的易感性，这两种酶对于寄生虫忍受巨噬细胞呼吸爆发都是可有可无的，分化为amastigotes并开始体内感染。这项研究介绍了锥虫cPRX功能的新视角，暴露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，利什曼原虫能适应两种酶缺失的发现对我们理解利什曼原虫感染及其治疗具有重要意义.重要的是,它质疑传统的观点,即吞噬作用过程中巨噬细胞的氧化反应是感染的主要障碍,以及cPRX是否适合作为利什曼病的药物靶标.
