title: Characterization of a silkworm thioredoxin peroxidase that is induced by external temperature stimulus and viral infection.
abstract: A thioredoxin peroxidase (TPx) that reduces H(2)O(2) was firstly characterized in the lepidopteran insect, silkworm Bombyx mori. The B. mori TPx (BmTPx) cDNA contains an open reading frame of 585 bp encoding 195 amino acid residues and possesses two cysteine residues that are characteristic of 2-Cys subgroup of peroxiredoxin family. The deduced amino acid sequence of the BmTPx cDNA showed 78% identity to Drosophila melanogaster (DmTPx-1), 73% to Aedes aegypti (AaTPx), and 54-48% to other insect 2-Cys TPx. The cDNA encoding BmTPx was expressed as a 25-kDa polypeptide in baculovirus-infected insect Sf9 cells. The purified recombinant BmTPx was shown to reduce H(2)O(2) in the presence of electrons donated by dithiothreitol and shown to be active in the presence of thioredoxin as electron donor. Northern blot analysis revealed the presence of BmTPx transcripts in all tissues examined. Western blot analysis showed the presence of the BmTPx in the fat body and midgut, but not in the hemolymph, suggesting the BmTPx is not secretable. When H(2)O(2) was injected into body cavity of B. mori larva, BmTPx mRNA expression was up-regulated in the fat body tissues. Interestingly, the expression levels of BmTPx enzyme in the fat body were particularly high when B. mori larva was exposed at low (4 degrees C) and high (37 degrees C) temperatures or baculovirus infection, suggesting that the BmTPx seems to play a protective role against oxidative stress caused by temperature stimuli and viral infection.
authors.affiliation: College of Natural Resources and Life Science, Dong-A University, Busan 604-714, Republic of Korea.
authors.forename: Kwang Sik
authors.initials: KS
authors.lastname: Lee
authors.forename: Seong Ryul
authors.initials: SR
authors.lastname: Kim
authors.forename: Nam Sook
authors.initials: NS
authors.lastname: Park
authors.forename: Iksoo
authors.initials: I
authors.lastname: Kim
authors.forename: Pil Dong
authors.initials: PD
authors.lastname: Kang
authors.forename: Bong Hee
authors.initials: BH
authors.lastname: Sohn
authors.forename: Kwang Ho
authors.initials: KH
authors.lastname: Choi
authors.forename: Seok Woo
authors.initials: SW
authors.lastname: Kang
authors.forename: Yeon Ho
authors.initials: YH
authors.lastname: Je
authors.forename: Sang Mong
authors.initials: SM
authors.lastname: Lee
authors.forename: Hung Dae
authors.initials: HD
authors.lastname: Sohn
authors.forename: Byung Rae
authors.initials: BR
authors.lastname: Jin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000201:enzymology* / Q000235:genetics / Q000821:virology*; D002460:Cell Line; D004790:Enzyme Induction; D007814:Larva / Q000201:enzymology; D008969:Molecular Sequence Data; D017924:Nucleopolyhedroviruses; D010544:Peroxidases / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D054464:Peroxiredoxins; D011994:Recombinant Proteins / Q000096:biosynthesis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013696:Temperature
chemical_list: D011994:Recombinant Proteins; D010544:Peroxidases; D054464:Peroxiredoxins