title: Cloning of a novel glutathione S-transferase 3 (GST3) gene and expressionanalysis in pearl oyster, Pinctada martensii.
abstract: 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.
authors.affiliation: 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.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Chen
authors.forename: Shu
authors.initials: S
authors.lastname: Xiao
authors.forename: Yuewen
authors.initials: Y
authors.lastname: Deng
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Du
authors.forename: Ziniu
authors.initials: Z
authors.lastname: Yu
mesh_terms: D000818:Animals; D001483:Base Sequence; D001555:Benzene Derivatives; D002104:Cadmium / Q000633:toxicity; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D020224:Expressed Sequence Tags; D040461:Gene Components; D005786:Gene Expression Regulation / Q000187:drug effects*; D005880:Gills / Q000378:metabolism; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism*; D043143:Hepatopancreas / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D018384:Oxidative Stress / Q000187:drug effects; D010544:Peroxidases / Q000378:metabolism; D049911:Pinctada / Q000201:enzymology* / Q000235:genetics; D017422:Sequence Analysis, DNA / Q000662:veterinary
chemical_list: D001555:Benzene Derivatives; D018076:DNA, Complementary; D002104:Cadmium; D010544:Peroxidases; D005982:Glutathione Transferase; C007164:cumene hydroperoxide