Thioredoxin from the silkworm, Bombyx mori: cDNA sequence, expression, and functional characterization.
A thioredoxin (Trx) gene was cloned from the silkworm, Bombyx mori. The B. mori Trx (BmTrx) cDNA contains an open reading frame of 318 bp encoding 106 amino acid residues with a conserved active site (CGPC). Northern blot analysis revealed the presence of BmTrx transcripts in all tissues examined. The cDNA encoding BmTrx was expressed as a 12-kDa polypeptide in baculovirus-infected insect Sf9 cells. The recombinant BmTrx proved to be biologically active, using an insulin reduction assay, and was also able to activate thioredoxin peroxidase from B. mori. When H2O2 or paraquat was injected into the body cavity of B. mori larvae, BmTrx mRNA expression was upregulated in the fat body tissue. In addition, the expression levels of BmTrx mRNA in the fat body were greatly increased when B. mori larvae were exposed to low or high temperatures, or injected with microorganisms. These results suggest that BmTrx possibly protects against oxidative stress caused by extreme temperatures and microbial infection as well as by intracellularly generated reactive oxygen species during metabolism.
Kim
Young Joo
YJ
College of Natural Resources and Life Science, Dong-A University, Busan 604-714, Republic of Korea.
Lee
Kwang Sik
KS
Kim
Bo Yeon
BY
Choo
Young Moo
YM
Sohn
Hung Dae
HD
Jin
Byung Rae
BR
D000818:Animals; D012831:Bombyx / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006540:Herbicides / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019476:Insect Proteins / Q000096:biosynthesis / Q000235:genetics*; D009928:Organ Specificity / Q000187:drug effects / Q000502:physiology; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010269:Paraquat / Q000494:pharmacology; D010544:Peroxidases / Q000378:metabolism; D054464:Peroxiredoxins; D017382:Reactive Oxygen Species / Q000378:metabolism; D013879:Thioredoxins / Q000096:biosynthesis / Q000235:genetics*
D018076:DNA, Complementary; D006540:Herbicides; D019476:Insect Proteins; D016877:Oxidants; D017382:Reactive Oxygen Species; D013879:Thioredoxins; D006861:Hydrogen Peroxide; D010544:Peroxidases; D054464:Peroxiredoxins; D010269:Paraquat