title: Flavodiiron protein from Trichomonas vaginalis hydrogenosomes: the terminal oxygen reductase.
abstract: Trichomonas vaginalis is one of a few eukaryotes that have been found to encode several homologues of flavodiiron proteins (FDPs). Widespread among anaerobic prokaryotes, these proteins are believed to function as oxygen and/or nitric oxide reductases to provide protection against oxidative/nitrosative stresses and host immune responses. One of the T. vaginalis FDP homologues is equipped with a hydrogenosomal targeting sequence and is expressed in the hydrogenosomes, oxygen-sensitive organelles that participate in carbohydrate metabolism and assemble iron-sulfur clusters. The bacterial homologues characterized thus far have been dimers or tetramers; the trichomonad protein is a dimer of identical 45-kDa subunits, each noncovalently binding one flavin mononucleotide. The protein reduces dioxygen to water but is unable to utilize nitric oxide as a substrate, similarly to its closest homologue from another human parasite Giardia intestinalis and related archaebacterial proteins. T. vaginalis FDP is able to accept electrons derived from pyruvate or NADH via ferredoxin and is proposed to play a role in the protection of hydrogenosomes against oxygen.
authors.affiliation: Department of Parasitology, Charles University, Vinicná, Prague, Czech Republic.
authors.forename: Tamara
authors.initials: T
authors.lastname: Smutná
authors.forename: Vera L
authors.initials: VL
authors.lastname: Gonçalves
authors.forename: Lígia M
authors.initials: LM
authors.lastname: Saraiva
authors.forename: Jan
authors.initials: J
authors.lastname: Tachezy
authors.forename: Miguel
authors.initials: M
authors.lastname: Teixeira
authors.forename: Ivan
authors.initials: I
authors.lastname: Hrdy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005288:Ferredoxins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005486:Flavin Mononucleotide / Q000378:metabolism; D008969:Molecular Sequence Data; D015388:Organelles / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity; D014246:Trichomonas vaginalis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics
chemical_list: D005288:Ferredoxins; D015800:Protozoan Proteins; D005486:Flavin Mononucleotide; D010088:Oxidoreductases; D010100:Oxygen