title: P-type proton ATPases are involved in intracellular calcium and proton uptake in the plant parasite Phytomonas francai.
abstract: The use of digitonin to permeabilize the plasma membrane of promastigotes of Phytomonas francai allowed the identification of two non-mitochondrial Ca(2+) compartments; one sensitive to ionomycin and vanadate (neutral or alkaline), possibly the endoplasmic reticulum, and another sensitive to the combination of nigericin plus ionomycin (acidic), possibly the acidocalcisomes. A P-type (phospho-intermediate form) Ca(2+)-ATPase activity was found to be responsible for intracellular Ca(2+) transport in these cells, with no evidence of a mitochondrial Ca(2+) transport activity. ATP-driven acidification of internal compartments in cell lysates and cells mechanically permeabilized was assayed spectrophotometrically with acridine orange. This activity was inhibited by low concentrations of vanadate and digitonin, was insensitive to bafilomycin A(1), and stimulated by Na(+) ions. Taken together, our results indicate that P-type ATPases are involved in intracellular Ca(2+) and H(+) transport in promastigotes of P. francai.
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Kildare
authors.initials: K
authors.lastname: Miranda
authors.forename: Anibal E
authors.initials: AE
authors.lastname: Vercesi
authors.forename: Rosana
authors.initials: R
authors.lastname: Catisti
authors.forename: Wanderley
authors.initials: W
authors.lastname: De Souza
authors.forename: Claudia O
authors.initials: CO
authors.lastname: Rodrigues
authors.forename: Roberto
authors.initials: R
authors.lastname: Docampo
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004072:Digitonin / Q000378:metabolism; D017136:Ion Transport; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D018942:Macrolides / Q000494:pharmacology; D009550:Nigericin / Q000494:pharmacology; D010935:Plant Diseases / Q000469:parasitology*; D017494:Proton Pumps / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D012964:Sodium / Q000502:physiology; D014351:Trypanosomatina / Q000201:enzymology*; D014638:Vanadates / Q000494:pharmacology
chemical_list: D007476:Ionophores; D018942:Macrolides; D017494:Proton Pumps; C057620:bafilomycin A; D014638:Vanadates; D015759:Ionomycin; D012964:Sodium; D006180:Proton-Translocating ATPases; D004072:Digitonin; D009550:Nigericin; D002118:Calcium