Zhang L, Lu Z
Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling, China.
Insect Mol Biol. 2015 Apr;24(2):203-12. doi: 10.1111/imb.12149. Epub 2014 Dec 16.
Peroxiredoxins (Prxs) play important roles in protecting organisms against damage caused by reactive oxygen species (ROS). In this study, we cloned a cDNA of Bombyx mori peroxiredoxin 5 (BmPrx5), which contained a 565-bp open reading frame for a 188-residue protein. Sequence analysis indicated that BmPrx5 belongs to the atypical 2-Cys peroxiredoxin family. Recombinant BmPrx5 purified from Escherichia coli showed antioxidant activity that removes H2 O2 and protects DNA from oxidative damage. Quantitative real-time PCR showed that the level of BmPrx5 mRNA in haemocytes increased early and decreased by 24 h after injection of H2 O2 whereas, in the fat body, the transcript level decreased at 6 h and increased at 12 h. Pseudomonas aeruginosa and Staphylococcus aureus infection resulted in higher levels of H2 O2 in the haemolymph and of BmPrx5 mRNA in haemocytes at 8 h postinfection. These data suggest that BmPrx5 acts as an antioxidant enzyme to protect the silkworm from oxidative damage induced by bacterial infection. Further study is needed to elucidate the exact role of BmPrx5 in the silkworm immune system.
过氧化物酶（Prxs）在保护生物体免受活性氧（ROS）造成的损伤方面发挥着重要作用。在本研究中，我们克隆了家蚕过氧化物酶5（BmPrx5）的cDNA，其包含一个565 bp的开放阅读框，编码一个188个氨基酸的蛋白质。序列分析表明，BmPrx5属于非典型2-半胱氨酸过氧化物酶家族。从大肠杆菌中纯化的重组BmPrx5表现出抗氧化活性，能够清除H2O2并保护DNA免受氧化损伤。定量实时PCR显示，注射H2O2后，血细胞中BmPrx5 mRNA水平早期升高，24小时后下降；而在脂肪体中，转录水平在6小时下降，12小时升高。铜绿假单胞菌和金黄色葡萄球菌感染导致感染后8小时血淋巴中H2O2水平升高，血细胞中BmPrx5 mRNA水平升高。这些数据表明，BmPrx5作为一种抗氧化酶，保护家蚕免受细菌感染诱导的氧化损伤。需要进一步研究以阐明BmPrx5在家蚕免疫系统中的具体作用。
