title: Molecular cloning and characterization of alpha-class glutathione S-transferase genes from the hepatopancreas of red sea bream, Pagrus major.
abstract: Two distinct cDNAs corresponding to GSTA1 and GSTA2 genes encoding glutathione S-transferases (GSTs) from the hepatopancreas of red sea bream, Pagrus major were cloned and sequenced. A comparison of the nucleotide sequences of GSTA1 and GSTA2 revealed 98% identity and their derived amino acid sequences had 96% similarity. Both genes could be classified as alpha-class GSTs on the basis of their amino acid sequence identity with other species. Genomic DNA cloning showed that both GSTA1 and GSTA2 genes consisted of six exons and five introns. In a comparison of genomic DNAs, the structures of GSTA1 and GSTA2 differed. In addition, Southern-blot analysis indicated that at least two kinds of alpha-class GSTs existed in the P. major genome. In order to biochemically characterize the recombinant enzymes (pmGSTA1-1 and pmGSTA2-2), both clones were highly expressed in Escherichia coli. The purified pmGSTA1-1 and pmGSTA2-2 exhibited glutathione conjugating activity toward 1-chloro-2,4-dinitrobenzene and glutathione peroxidase activity toward cumene hydroperoxide, while neither pmGSTs show detectable activity toward 1,2-dichloro-4-nitrobenzene, ethacrynic acid, 4-hydroxynonenal, or p-nitrobenzyl chloride. Despite their high level of amino acid sequence identity, the pmGSTs had quite different enzyme-kinetic parameters.
authors.affiliation: Department of Life Science, Faculty of Bioresources, Mie University, 1515 Kamihama, Tsu, Mie 514-8507, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Konishi
authors.forename: Keitaro
authors.initials: K
authors.lastname: Kato
authors.forename: Toshiyoshi
authors.initials: T
authors.lastname: Araki
authors.forename: Kentaro
authors.initials: K
authors.lastname: Shiraki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takagi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tamaru
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003116:Color; D018076:DNA, Complementary / Q000235:genetics; D005982:Glutathione Transferase / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D043143:Hepatopancreas / Q000201:enzymology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021541:Sea Bream / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D018076:DNA, Complementary; D020033:Protein Isoforms; D011994:Recombinant Proteins; D005982:Glutathione Transferase