Characterization of a silkworm thioredoxin peroxidase that is induced by external temperature stimulus and viral infection
Autor(es): Lee, KS; Kim, SR; Park, NS; Kim, I; Kang, PD; Sohn, BH; Choi, KH; Kang, SW; Je, YH; Lee, SM; Sohn, HD; Jin, BR
Resumo: A thioredoxin peroxidase (TPx) that reduces H 0, 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 SP) cells. The purified recombinant BmTPx was shown to reduce H2O2 in the presence or 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 H2O2 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 degreesC) and high (37 degreesC) temperatures or baculovirus infection, suggesting that the BmTPx seems to play a protective role against oxidative stress caused by temperature stimuli and viral infection. (C) 2004 Elsevier Ltd. All rights reserved.
Palavras-Chave: Antioxidant enzyme; Bombyx mori; Insect; Oxidative stress; Peroxiredoxin; Reactive oxygen species; Silkworm; Thioredoxin peroxidase
Imprenta: Insect Biochemistry and Molecular Biology, v. 35, n. 1, p. 73-84, 2005
Identificador do objeto digital: 10.1016/j.ibmb.2004.09.008
Descritores: Aedes aegypti - Biochemistry ; Aedes aegypti - DNA
Data de publicação: 2005
