Key Laboratory of Marine Bio-resources Sustainable Utilization, CAS, Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China.
Fish Shellfish Immunol. 2011 Dec;31(6):823-30. doi: 10.1016/j.fsi.2011.07.023. Epub 2011 Jul 27.
Microsomal glutathione S-transferase (MGST) functions in cellular defense against xenobiotics and provides protection against the action of lipid hydroperoxides produced as a consequence of oxidative stress. In this study, a full-length cDNA encoding MGST3 (referred to as PmMGST3) was identified from the pearl oyster, Pinctada martensii by a combination of expressed sequence tag (EST) analysis and rapid amplification of cDNA ends (RACE). The full-length cDNA of PmMGST3 is 971 bp and contains a 5' UTR of 39 bp, a 3' UTR of 491 bp with a canonical polyadenylation signal sequence (AATAAA), and an open reading frame (ORF) of 447 bp encoding a polypeptide of 146 residues. The deduced polypeptide contains a conserved motif (FNCx(1)QRx(2)H) characteristic of the MGST3 subfamily. The PmMGST3 transcript could be detected in all tissues tested, with highest transcript level seen in hepatopancreas. Cadmium treatment significantly increased PmMGST3 mRNA levels in gill and hepatopancreas, while bacterial challenge initially depressed mRNA levels and then increased its level in haemocytes, gill and hepatopancreas in a time-dependent manner. In an assay using cumene hydroperoxide as a substrate, we demonstrated that PmMGST3 possesses glutathione-dependent peroxidase activity. These results suggest that PmMGST3 plays an important role in cellular defense against oxidative stress caused by cadmium and bacteria.
微粒体谷胱甘肽 S-转移酶 (MGST) 在细胞防御外来物质和提供保护免受脂质氢过氧化物的作用，这些脂质氢过氧化物是氧化应激的结果。在这项研究中，通过表达序列标签 (EST) 分析和快速扩增 cDNA 末端 (RACE) 的组合，从珍珠贝 (Pinctada martensii) 中鉴定出一个编码 MGST3 (称为 PmMGST3) 的全长 cDNA。PmMGST3 的全长 cDNA 为 971 bp，包含一个 5'UTR 为 39 bp，3'UTR 为 491 bp，带有一个典型的多聚腺苷酸化信号序列 (AATAAA)，和一个开放阅读框 (ORF) 为 447 bp，编码一个 146 个氨基酸的多肽。推导的多肽含有一个保守的基序 (FNCx(1)QRx(2)H)，这是 MGST3 亚家族的特征。在所有测试的组织中都可以检测到 PmMGST3 的转录本，在肝胰腺中检测到的转录本水平最高。镉处理显著增加了鳃和肝胰腺中 PmMGST3 mRNA 的水平，而细菌挑战最初降低了 mRNA 的水平，然后在时间依赖性的方式下在血细胞、鳃和肝胰腺中增加了其水平。在使用 cumene hydroperoxide 作为底物的测定中，我们证明了 PmMGST3 具有谷胱甘肽依赖性过氧化物酶活性。这些结果表明，PmMGST3 在细胞防御镉和细菌引起的氧化应激中发挥重要作用。
