title: cDNA cloning and mRNA expression of a selenium-dependent glutathione peroxidase from Zhikong scallop Chlamys farreri.
abstract: 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.
authors.affiliation: The Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Rd., Shandong, Qingdao 266071, China.
authors.forename: Changkao
authors.initials: C
authors.lastname: Mu
authors.forename: Duojiao
authors.initials: D
authors.lastname: Ni
authors.forename: Jianmin
authors.initials: J
authors.lastname: Zhao
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.forename: Limei
authors.initials: L
authors.lastname: Qiu
authors.forename: Ming
authors.initials: M
authors.lastname: Cong
mesh_terms: D020413:3' Untranslated Regions; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D005979:Glutathione Peroxidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D053526:Listonella / Q000502:physiology; D008969:Molecular Sequence Data; D049897:Pectinidae / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism; D017279:Selenocysteine / Q000032:analysis; D016415:Sequence Alignment
chemical_list: D020413:3' Untranslated Regions; D018076:DNA, Complementary; D012333:RNA, Messenger; D017279:Selenocysteine; D005979:Glutathione Peroxidase