Paracoccidioides brasiliensis is a temperature-dependent dimorphic fungus that causes systemic paracoccidioidomycosis, a granulomatous disease. The massive production of reactive oxygen species (ROS) by the host's cellular immune response is an essential strategy to restrain the fungal growth. Among the ROS, the hydroperoxides are very toxic antimicrobial compounds and fungal peroxidases are part of the pathogen neutralizing antioxidant arsenal against the host's defense. Among them, the peroxiredoxins are highlighted, since some estimates suggest that they are capable of decomposing most of the hydroperoxides generated in the host's mitochondria and cytosol. We presently characterized a unique P. brasiliensis 1-Cys peroxiredoxin (PbPrx1). Our results reveal that it can decompose hydrogen peroxide and organic hydroperoxides very efficiently. We showed that dithiolic, but not monothiolic compounds or heterologous thioredoxin reductant systems, were able to retain the enzyme activity. Structural analysis revealed that PbPrx1 has an α/β structure that is similar to the 1-Cys secondary structures described to date and that the quaternary conformation is represented by a dimer, independently of the redox state. We investigated the PbPrx1 localization using confocal microscopy, fluorescence-activated cell sorter, and immunoblot, and the results suggested that it localizes both in the cytoplasm and at the cell wall of the yeast and mycelial forms of P. brasiliensis, as well as in the yeast mitochondria. Our present results point to a possible role of this unique P. brasiliensis 1-Cys Prx1 in the fungal antioxidant defense mechanisms.

巴西副球菌是一种温度依赖性双态真菌，可引起全身性球菌性肉芽肿病。宿主的细胞免疫反应大量产生活性氧（ROS）是抑制真菌生长的重要策略。在ROS中，氢过氧化物是剧毒的抗微生物化合物，而真菌过氧化物酶是病原体中和抗氧化剂砷以防宿主防御的一部分。其中，过氧化物酶是突出的，因为一些估计表明它们能够分解宿主线粒体和细胞质中产生的大多数氢过氧化物。我们目前的特色是巴西假单胞菌1-半胱氨酸过氧化物酶（PbPrx1）。我们的结果表明，它可以非常有效地分解过氧化氢和有机氢过氧化物。我们表明，二硫醇而不是单硫醇化合物或异源硫氧还蛋白还原剂系统能够保留酶活性。结构分析表明，PbPrx1具有与迄今描述的1-Cys二级结构相似的α/β结构，且四级构象由二聚体表示，与氧化还原状态无关。我们使用共聚焦显微镜，荧光激活细胞分选仪和免疫印迹研究了PbPrx1的定位，结果表明它既定位于酵母的细胞质中，又定位于酵母的菌丝体和菌丝体中。巴西假单胞菌，以及酵母线粒体。我们目前的结果表明这种独特的作用巴西假单胞菌 1-Cys Prx1在真菌中具有抗氧化防御机制。