title: Trypanosoma rangeli: differential expression of ecto-phosphatase activities in response to inorganic phosphate starvation.
abstract: In this work, we showed that living cells of Trypanosoma rangeli express different ecto-phosphatase activities in response to different inorganic phosphate (Pi) concentrations in the culture medium. The ecto-phosphatase activity from T. rangeli grown at low-Pi concentration was inhibited by the increase of the pH, while the ecto-phosphatase of the cells grown at high Pi concentration was not modulated by the change of the pH of the medium. Okadaic acid inhibited only the ecto-phosphatase activity from cells grown at low-Pi concentration but not the ecto-phosphatase activity from cells grown at high-Pi concentration. Accordingly, phosphatase activity from T. rangeli grown at low Pi concentration was able to hydrolyze P-serine and P-threonine at high rate but not P-tyrosine. The phosphatase activity from T. rangeli grown at high-Pi concentration was able to hydrolyze P-serine, P-threonine and P-tyrosine with the same rate. The addition of anterior midgut homogenate of Rhodnius prolixus on the epimastigotes suspension inhibited the enzyme activity of T. rangeli grown at low-Pi concentration. On the other hand, anterior midgut homogenate had no effect in the ecto-phosphatase of T. rangeli maintained at high-Pi concentration. Altogether, the results described here indicate that ecto-phosphatase activities hydrolyzing phosphorylated compounds present in the extracellular medium of T. rangeli are regulated by the external Pi concentration.
authors.affiliation: Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, UFRJ, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, RJ, Brazil.
authors.forename: Claudia Fernanda
authors.initials: CF
authors.lastname: Dick
authors.forename: André Luiz Araújo
authors.initials: AL
authors.lastname: Dos-Santos
authors.forename: André L
authors.initials: AL
authors.lastname: Fonseca-de-Souza
authors.forename: Juliana
authors.initials: J
authors.lastname: Rocha-Ferreira
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Meyer-Fernandes
mesh_terms: D000818:Animals; D003470:Culture Media; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007303:Insect Vectors / Q000469:parasitology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009596:Nitrophenols / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D012239:Rhodnius / Q000469:parasitology; D014345:Trypanosoma / Q000201:enzymology*
chemical_list: D003470:Culture Media; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D010710:Phosphates; C008644:nitrophenylphosphate; D007770:L-Lactate Dehydrogenase; D010744:Phosphoric Monoester Hydrolases