1. A unique thioredoxin of the parasitic nematode Haemonchus contortus with glutaredoxin activity.
- Author
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Sotirchos IM, Hudson AL, Ellis J, and Davey MW
- Subjects
- Amino Acid Motifs, Animals, Arginine, Catalytic Domain, Cytoprotection physiology, Gene Expression, Gene Expression Regulation, Enzymologic physiology, Glutaredoxins chemistry, Glutathione chemistry, Haemonchus growth & development, Insulin chemistry, Life Cycle Stages physiology, Oxidation-Reduction, Oxidative Stress physiology, Substrate Specificity, Thioredoxin-Disulfide Reductase chemistry, Thioredoxin-Disulfide Reductase metabolism, Thioredoxins chemistry, Thioredoxins genetics, Transgenes, Glutaredoxins metabolism, Glutathione metabolism, Haemonchus metabolism, Insulin metabolism, Thioredoxins metabolism
- Abstract
The dependency of parasites on the cellular redox systems has led to their investigation as novel drug targets. Defence against oxidative damage is through the thioredoxin and glutathione systems. The classic thioredoxin is identified by the active site Cys-Gly-Pro-Cys (CGPC). Here we describe the identification of a unique thioredoxin in the parasitic nematode, Haemonchus contortus. This thioredoxin-related protein, termed HcTrx5, has an arginine in its active site (Cys-Arg-Ser-Cys; CRSC) that is not found in any other organism. Recombinant HcTrx5 was able to reduce the disulfide bond in insulin, and be regenerated by mammalian thioredoxin reductase with a K(m) 2.19+/-1.5 microM, similar to the classic thioredoxins. However, it was also able to reduce insulin when glutathione and glutathione reductase replaced the thioredoxin reductase. When coupled with H. contortus peroxiredoxin, HcTrx5 was active using either the thioredoxin reductase or the glutathione and glutathione reductase. HcTrx5 is expressed through the life cycle, with highest expression in the adult stage. The unique activity of this thioredoxin makes it a potential drug target for the control of this parasite.
- Published
- 2009
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