Levick M P, Tetaud E, Fairlamb A H, Blackwell J M
Department of Medicine, University of Cambridge, Addenbrooke's Hospital, UK.
Mol Biochem Parasitol. 1998 Oct 30;96(1-2):125-37. doi: 10.1016/s0166-6851(98)00122-4.
Leishmania spp. encounter damaging oxygen metabolites from endogenous metabolic processes as well as from exogenous sources, such as inside the gut of the sandfly vector and within host macrophages. The recently described peroxidoxin protein family form part of a novel pathway for metabolising hydrogen peroxide that, in trypanosomatids, links peroxide reduction to NADPH oxidation via trypanothione. Here we report the cloning and characterisation of the Leishmania major peroxidoxin gene, tryparedoxin peroxidase (TryP). TryP is a multi-copy gene arranged in a complex tandem array located on the size polymorphic homologues of chromosome 15. Northern analysis showed that TryP expresses a single 1.6 kb mRNA throughout promastigote development. TryP encodes a 22-kDa protein with two conserved cysteine-containing domains that defines it as a 2-Cys peroxidoxin. Purified recombinant TryP protein catabolised hydrogen peroxide in the presence of the tryparedoxin homologue from Crithidia fasciculata (Cf-TryX), trypanothione, trypanothione reductase and NADPH. The demonstration that L. major utilises a three-protein peroxidase system confirms that this is a mechanism of protection against oxidative damage in this parasite.
利什曼原虫会遭遇来自内源性代谢过程以及外源性来源（如在白蛉媒介的肠道内和宿主巨噬细胞内）的具有破坏性的氧代谢产物。最近描述的过氧化物酶蛋白家族构成了一条代谢过氧化氢的新途径的一部分，在锥虫中，该途径通过锥虫硫醇将过氧化物还原与NADPH氧化联系起来。在此，我们报告了硕大利什曼原虫过氧化物酶基因——锥虫硫氧还蛋白过氧化物酶（TryP）的克隆与特性分析。TryP是一个多拷贝基因，以复杂的串联阵列形式排列在15号染色体大小多态性同源物上。Northern分析表明，在整个前鞭毛体发育过程中，TryP表达单一的1.6 kb mRNA。TryP编码一种22 kDa的蛋白质，具有两个保守的含半胱氨酸结构域，这将其定义为一种2 - 半胱氨酸过氧化物酶。在来自fasiculata隐鞭虫（Cf - TryX）的锥虫硫氧还蛋白同源物、锥虫硫醇、锥虫硫醇还原酶和NADPH存在的情况下，纯化的重组TryP蛋白能够分解过氧化氢。硕大利什曼原虫利用一种三蛋白过氧化物酶系统的证明证实了这是该寄生虫抵御氧化损伤的一种机制。
