title: Leishmania amazonensis: effects of heat shock on ecto-ATPase activity.
abstract: In this work we demonstrated that promastigotes of Leishmania amazonensis exhibit an Mg-dependent ecto-ATPase activity, which is stimulated by heat shock. The Mg-dependent ATPase activity of cells grown at 22 and 28 degrees C was 41.0+/-5.2 nmol Pi/h x 10(7)cells and 184.2+/-21.0 nmol Pi/h x 10(7)cells, respectively. When both promastigotes were pre-incubated at 37 degrees C for 2h, the ATPase activity of cells grown at 22 degrees C was increased to 136.4+/-10.6 nmol Pi/h x 10(7) whereas that the ATPase activity of cells grown at 28 degrees C was not modified by the heat shock (189.8+/-10.3 nmol Pi/h x 10(7)cells). It was observed that Km of the enzyme from cells grown at 22 degrees C (Km=980.2+/-88.6 microM) was the same to the enzyme from cells grown at 28 degrees C (Km=901.4+/-91.9 microM). In addition, DIDS (4,4'-diisothiocyanatostilbene 2,2'-disulfonic acid) and suramin, two inhibitors of ecto-ATPases, also inhibited similarly the ATPase activities from promastigotes grown at 22 and 28 degrees C. We also observed that cells grown at 22 degrees C exhibit the same ecto-phosphatase and ecto 3'- and 5'-nucleotidase activities than cells grown at 28 degrees C. Interestingly, cycloheximide, an inhibitor of protein synthesis, suppressed the heat-shock effect on ecto-ATPase activity of cells grown at 22 degrees C were exposed at 37 degrees C for 2h. A comparison between the stimulation of the Mg-dependent ecto-ATPase activity of virulent and avirulent promastigotes by the heat shock showed that avirulent promastigotes had a higher stimulation than virulent promastigotes after heat stress.
authors.affiliation: Faculdade de Enfermagem-FENF, Centro Biomédico, Universidade do Estado do Rio de Janeiro-UERJ, Av. 28 de setembro 87, Vila Isabel, 20551-030, Rio de Janeiro, RJ, Brazil.
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Peres-Sampaio
authors.forename: Elmo Eduardo
authors.initials: EE
authors.lastname: de Almeida-Amaral
authors.forename: Naira Ligia Lima
authors.initials: NL
authors.lastname: Giarola
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Meyer-Fernandes
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001938:Brazil; D006224:Cricetinae; D006358:Hot Temperature; D006801:Humans; D006868:Hydrolysis; D007894:Leishmania mexicana / Q000201:enzymology* / Q000472:pathogenicity; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology; D013997:Time Factors; D014774:Virulence
chemical_list: D000255:Adenosine Triphosphate; D009597:4-Nitrophenylphosphatase; D000251:Adenosine Triphosphatases; C027201:ectoATPase