title: Kinetic characterization and gene expression of adenosine deaminase in intact trophozoites of Trichomonas vaginalis.
abstract: Trichomonas vaginalis is a parasite that resides in the human urogenital tract and causes trichomonosis, the most prevalent nonviral sexually transmitted disease. Nucleoside triphosphate diphosphohydrolase (NTPDase), which hydrolyzes extracellular di- and triphosphate nucleotides, and ecto-5'-nucleotidase, which hydrolyzes AMP, have been characterized in T. vaginalis. The aim of this study was to characterize the adenosine deaminase (ADA) activity in intact trophozoites of T. vaginalis. A strong inhibition in adenosine deamination was observed in the presence of calcium and magnesium, which was prevented by EDTA. The apparent K(M) value for adenosine was 1.13 ± 0.07mM. The calculated V(max) was 2.61 ± 0.054 nmol NH(3) min(-1) mg(-1) protein. Adenosine deamination was inhibited in the presence of erythro-9-(2-hydroxy-3-nonyl)adenine. Semi-quantitative reverse transcriptase-PCR experiments were performed and both ADA-related genes ada(125) and ada(231) mRNA were expressed, although ada(231) in higher quantity when compared with the ada(125) : α-tubulin ratio. Furthermore, a phylogenetic analysis showed that the T. vaginalis sequences formed a clade with Entamoeba histolytica and Dictyostelium discoideum sequences, and it strongly suggests homologous functions in the T. vaginalis genome. The presence of ADA activity in T. vaginalis may be important to modulate the adenosine/inosine levels during infection and, consequently, to maintain the anti-inflammatory properties through different nucleoside-signalling mechanisms.
authors.affiliation: Laboratório de Pesquisa em Parasitologia, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Marina
authors.initials: M
authors.lastname: Weizenmann
authors.forename: Amanda Piccoli
authors.initials: AP
authors.lastname: Frasson
authors.forename: Muriel Primon
authors.initials: MP
authors.lastname: de Barros
authors.forename: Patrícia de Brum
authors.initials: Pde B
authors.lastname: Vieira
authors.forename: Denis Broock
authors.initials: DB
authors.lastname: Rosemberg
authors.forename: Geraldo Attilio
authors.initials: GA
authors.lastname: De Carli
authors.forename: Maurício Reis
authors.initials: MR
authors.lastname: Bogo
authors.forename: Carla Denise
authors.initials: CD
authors.lastname: Bonan
authors.forename: Tiana
authors.initials: T
authors.lastname: Tasca
mesh_terms: D000243:Adenosine Deaminase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007700:Kinetics; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014247:Trichomonas Vaginitis / Q000469:parasitology; D014246:Trichomonas vaginalis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D053058:Trophozoites / Q000737:chemistry / Q000201:enzymology* / Q000254:growth & development
chemical_list: D015800:Protozoan Proteins; D000243:Adenosine Deaminase