Identification and biochemical characterization of two novel peroxiredoxins in a liver fluke, Clonorchis sinensis
Identification and biochemical characterization of two novel peroxiredoxins in a liver fluke, Clonorchis sinensis
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DOI：
10.1017/s0031182011000813
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发表时间：
2011-08-01
期刊：
影响因子：
2.4
通讯作者：
Kong, Y.
中科院分区：
文献类型：
--
作者：
Bae, Y. -A.;Kim, S. -H.;Kong, Y.
我们在华支睾吸虫中发现了两个编码不同2-半胱氨酸过氧化还蛋白(2-Cys Peroxiredoxins，PRxs)的新基因，分别命名为CsPRx2和CsPRx3，它们侵入人的肝胆管。随着寄生虫的发育，CsPRx2基因的表达呈时间上的增加，其蛋白产物几乎在成虫的所有部位都可检测到，包括被膜下和排泄分泌产物。相反，CsPRx3的表达暂时维持在基础水平，并主要局限于各种组织/器官的内部。重组形式的CsPRx蛋白在硫氧还蛋白或谷胱甘肽(GSH)的存在下表现出对各种过氧化氢的还原活性，尽管它们分别倾向于以H_2O_2和GSH作为催化底物和电子供体。稳态动力学研究表明，CsPrx蛋白遵循可饱和的Michaelis-Menten型方程，其催化效率(k(CAT)/K-m)在10(3)~10(4)M~(-1)S(-1)之间，略低于所研究的其他PRX蛋白(10(4)~10(5)M~(-1)S(-1))。CsPRx2和CsPRx3特异的表达模式和组织分布可能表明抗氧化酶在保护蠕虫免受氧化损伤方面具有不同的生理功能。
We identified 2 novel genes encoding different 2-Cys peroxiredoxins (PRxs), designated CsPRx2 and CsPRx3, in Clonorchis sinensis, which invades the human hepatobiliary tracts. The CsPRx2 gene expression was temporally increased along with the parasite's development and its protein product was detected in almost all parts of adult worms including subtegument, as well as excretory-secretory products. Conversely, CsPRx3 expression was temporally maintained at a basal level and largely restricted within interior parts of various tissues/organs. The recombinant forms of CsPRx proteins exhibited reducing activity against various hydroperoxides in the presence of either thioredoxin or glutathione (GSH) as a reducing equivalent, although they preferred H2O2 and GSH as a catalytic substrate and electron donor, respectively. A steady-state kinetic study demonstrated that the CsPRx proteins followed a saturable, Michaelis-Menten-type equation with the catalytic efficiencies (k(cat)/K-m) ranging from 10(3) to 10(4) M-1 s(-1), somewhat lower than those for other PRxs studied (10(4)-10(5) M-1 s(-1)). The expression patterns and histological distributions specific to CsPRx2 and CsPRx3 might suggest different physiological functions of the antioxidant enzymes in protecting the worms against oxidative damage.