title: OsmC and incomplete glycine decarboxylase complex mediate reductive detoxification of peroxides in hydrogenosomes of Trichomonas vaginalis.
abstract: Osmotically inducible protein (OsmC) and organic hydroperoxide resistance protein (Ohr) are small, thiol-dependent peroxidases that comprise a family of prokaryotic protective proteins central to the defense against deleterious effects of organic hydroperoxides, which are reactive molecules that are formed during interactions between the host immune system and pathogens. Trichomonas vaginalis, a sexually transmitted parasite of humans, possesses OsmC homologues in its hydrogenosomes, anaerobic mitochondrial organelles that harbor enzymes and pathways that are sensitive to oxidative damage. The glycine decarboxylase complex (GDC), which consists of four proteins (i.e., L, H, P and T), is in eukaryotes exclusively mitochondrial enzymatic system that catalyzes oxidative decarboxylation and deamination of glycine. However, trichomonad hydrogenosomes contain only the L and H proteins, whose physiological functions are unknown. Here, we found that the hydrogenosomal L and H proteins constitute a lipoate-dependent redox system that delivers electrons from reduced nicotinamide adenine dinucleotide (NADH) to OsmC for the reductive detoxification of peroxides. Our searches of genome databases revealed that, in addition to prokaryotes, homologues of OsmC/Ohr family proteins with predicted mitochondrial localization are present in various eukaryotic lineages. Therefore, we propose that the novel OsmC-GDC-based redox system may not be limited to T. vaginalis.
authors.affiliation: Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic.
authors.forename: Eva
authors.initials: E
authors.lastname: Nývltová
authors.affiliation: Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic.
authors.forename: Tamara
authors.initials: T
authors.lastname: Smutná
authors.affiliation: Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Tachezy
authors.affiliation: Department of Parasitology, Charles University in Prague, Faculty of Science, Prague, Czech Republic. Electronic address: hrdy@cesnet.cz.
authors.forename: Ivan
authors.initials: I
authors.lastname: Hrdý
mesh_terms: D000595:Amino Acid Sequence; D061245:Axenic Culture; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D050959:Glycine Decarboxylase Complex / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007700:Kinetics; D050216:Metabolic Detoxication, Phase I / Q000235:genetics; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011485:Protein Binding; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014246:Trichomonas vaginalis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D015800:Protozoan Proteins; D011994:Recombinant Proteins; D006861:Hydrogen Peroxide; D010544:Peroxidases; C058652:thiol-dependent peroxidase; D050959:Glycine Decarboxylase Complex
keywords: Glycine decarboxylase complex; Hydrogenosomes; Lipoate; OsmC; Peroxide; Trichomonas