title: Identification and cloning of a selenium-dependent glutathione peroxidase from tiger shrimp, Penaeus monodon, and its transcription following pathogen infection and related to the molt stages.
abstract: Complementary (c)DNA encoding glutathione peroxidase (GPx) messenger (m)RNA of the tiger shrimp Penaeus monodon was obtained from haemocytes by a reverse-transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) method. The 1321-bp cDNA contained an open reading frame (ORF) of 564bp, a 69-bp 5'-untranslated region (UTR), and a 688-bp 3'-UTR containing a poly A tail and a conserved selenocysteine insertion sequence (SECIS) element. The molecular mass of the deduced amino acid (aa) sequence (188 aa) was 21.05kDa long with an estimated pI of 7.68. It contains a putative selenocysteine residue which is encoded by the unusual stop codon, (190)TGA(192), and forms the active site with residues Glu(75) and Trp(143). Comparison of amino acid sequences showed that tiger shrimp GPx is more closely related to vertebrate GPx1, in accordance with those in Litopenaeus vannamei and Macrobrachium rosenbergii. GPx cDNA was synthesised in lymphoid organ, gills, heart, haemocytes, the hepatopancreas, muscles, and intestines. After injected with either Photobacterium damsela or white spot syndrome virus (WSSV), the respiratory bursts of shrimp significantly increased in order to kill the pathogen, and induced increases in the activities of superoxide dismutase and GPx, and regulation in the expression of cloned GPx mRNA to protect cells against damage from oxidation. The GPx expression significantly increased at stage D(0/1), and then gradually decreased until stage C suggesting that the cloned GPx might play a role in the molt regulation of shrimp.
authors.affiliation: Institute of Zoology, National Taiwan University, Taipei 10617, Taiwan, ROC.
authors.forename: Kuan-Fu
authors.initials: KF
authors.lastname: Liu
authors.forename: Maw-Sheng
authors.initials: MS
authors.lastname: Yeh
authors.forename: Guang-Hsiung
authors.initials: GH
authors.lastname: Kou
authors.forename: Winton
authors.initials: W
authors.lastname: Cheng
authors.forename: Chu-Fang
authors.initials: CF
authors.lastname: Lo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D004266:DNA Virus Infections / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D005979:Glutathione Peroxidase / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D016905:Gram-Negative Bacterial Infections / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D006434:Hemocytes / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008969:Molecular Sequence Data; D018978:Molting / Q000235:genetics; D033561:Penaeidae; D010776:Photobacterium / Q000276:immunology* / Q000472:pathogenicity; D010802:Phylogeny; D016897:Respiratory Burst; D017279:Selenocysteine / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D046848:White spot syndrome virus 1 / Q000276:immunology* / Q000472:pathogenicity
chemical_list: D017279:Selenocysteine; D005979:Glutathione Peroxidase