title: Preferential regeneration of thioredoxin from parasitic flatworm Fasciola gigantica using glutathione system.
abstract: The maintenance of cellular redox homeostasis is a crucial adaptive problem faced by parasites, and its disruption can shift the biochemical balance toward the host. The thioredoxin (Trx) system plays a key role in redox metabolism and defense against oxidative stress. In this study, biochemical experiments were performed on Fasciola gigantica Thioredoxin1 (FgTrx1). The recombinant FgTrx1 exists as a monomer and catalyzes the reduction of insulin. FgTrx1 is preferentially regenerated by the glutathione (GSH) system using glutathione reductase (GR). The regeneration of FgTrx1 by the conventional Trx system is much less as compared to the GSH system, suggesting that FgTrx1 could be acting as glutaredoxin (Grx). DNA nicking and hydroperoxide assay suggests that it protects the DNA from radical-induced oxidative damage. Thus, FgTrx1 might play a role in parasite survival as it can regenerate itself even in the absence of the canonical Trx system and also protect the cells from ROS induced damage. Further, we propose that the GR activity of FgTrx1 is not restricted to -CXXC- motif but is regulated by residues present in close proximity to the -CXXC- motif, through manipulation of the redox potential or the pKa of the active site Cys residues.
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India.
authors.forename: Ankita
authors.initials: A
authors.lastname: Gupta
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India.
authors.forename: Tripti
authors.initials: T
authors.lastname: Pandey
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India.
authors.forename: Bijay
authors.initials: B
authors.lastname: Kumar
authors.affiliation: Molecular and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India. Electronic address: timir.tripathi@gmail.com.
authors.forename: Timir
authors.initials: T
authors.lastname: Tripathi
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D055162:Biocatalysis / Q000187:drug effects; D001681:Biological Assay; D003198:Computer Simulation; D005209:Fasciola / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism; D010271:Parasites / Q000378:metabolism*; D055503:Protein Multimerization / Q000187:drug effects; D011994:Recombinant Proteins / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D007328:Insulin; D011994:Recombinant Proteins; D013879:Thioredoxins; D005978:Glutathione
keywords: Antioxidant; Free radicals; Glutathione; Liver fluke; Oxidative stress; Parasite; Redox; Thioredoxin