The Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Rd., Shandong, Qingdao 266071, China.
Comp Biochem Physiol B Biochem Mol Biol. 2010 Oct;157(2):182-8. doi: 10.1016/j.cbpb.2010.06.002. Epub 2010 Jun 18.
The glutathione peroxidases are essential enzymes of the cellular antioxidant defence system. In the present study, the full-length cDNA sequence encoding an extracellular glutathione peroxidase (designated CfGPx3) was isolated from Zhikong scallop Chlamys farreri. The complete cDNA was of 1194 bp, containing a 5' untranslated region (UTR) of 50 bp, a 3' UTR of 490 bp and an open reading frame (ORF) of 654 bp encoding a polypeptide of 217 amino acids. CfGPx3 possessed all the conserved features critical for the fundamental structure and function of glutathione peroxidase, such as the selenocysteine encoded by stop codon UGA, the GPx signature motif (96LGVPCNQF103) and the active site motif (179WNFEKF184). The high similarity of CfGPx3 with GPx from other organisms indicated that CfGPx3 should be a new member of the glutathione peroxidase family. By fluorescent quantitative real-time PCR, the CfGPx3 mRNA was universally detected in the tissues of haemocytes, gill, gonad, muscle and hepatopancreas with the highest expression in hepatopancreas. After scallops were challenged by Listonella anguillarum, the expression level of CfGPx3 transcript in haemocytes was significantly up-regulated (P<0.05) at 8h post challenge. These results suggested that CfGPx3 was potentially involved in the immune response of scallops and perhaps contributed to the protective effects against oxidative stress.
谷胱甘肽过氧化物酶是细胞抗氧化防御系统的必需酶。本研究从栉孔扇贝中分离出一种细胞外谷胱甘肽过氧化物酶（命名为 CfGPx3）的全长 cDNA 序列。完整的 cDNA 长 1194bp，包含 5'非翻译区（UTR）50bp，3'UTR 490bp 和一个开放阅读框（ORF）654bp，编码 217 个氨基酸的多肽。CfGPx3 具有谷胱甘肽过氧化物酶基本结构和功能所必需的所有保守特征，如终止密码 UGA 编码的硒代半胱氨酸、GPx 特征基序（96LGVPCNQF103）和活性位点基序（179WNFEKF184）。CfGPx3 与其他生物体的 GPx 高度相似，表明 CfGPx3 应该是谷胱甘肽过氧化物酶家族的一个新成员。通过荧光定量实时 PCR，在血细胞、鳃、性腺、肌肉和肝胰腺组织中普遍检测到 CfGPx3 mRNA，在肝胰腺中表达量最高。在栉孔扇贝受到鳗弧菌攻击后，血细胞中 CfGPx3 转录本的表达水平在 8h 时显著上调（P<0.05）。这些结果表明 CfGPx3 可能参与了扇贝的免疫反应，并可能有助于对抗氧化应激的保护作用。
