title: Rotenone-sensitive mitochondrial potential in Phytomonas serpens: electrophoretic Ca(2+) accumulation.
abstract: Phytomonas sp. are flagellated trypanosomatid plant parasites that cause diseases of economic importance in plantations of coffee, oil palm, cassava and coconuts. Here we investigated Ca(2+) uptake by the vanadate-insensitive compartments using permeabilized Phytomonas serpens promastigotes. This uptake occurs at a rate of 1.13+/-0.23 nmol Ca(2+) mg x protein(-1) min(-1). It is completely abolished by the H(+) ionophore FCCP and by valinomycin and nigericin. It is also inhibited by 2 microM ruthenium red, which, at this low concentration, is known to inhibit the mitochondrial calcium uniport. Furthermore, salicylhydroxamic acid (SHAM) and propylgallate, specific inhibitors of the alternative oxidase in plant and parasite mitochondria, are also effective as inhibitors of the Ca(2+) transport. These compounds abolish the membrane potential that is monitored with safranine O. Rotenone, an inhibitor of NADH-CoQ oxidoreductase, can also dissipate 100% of the membrane potential. It is suggested that the mitochondria of P. serpens can be energized via oxidation of NADH in a pathway involving the NADH-CoQ oxidoreductase and the alternative oxidase to regenerate the ubiquinone. The electrochemical H(+) gradient can be used to promote Ca(2+) uptake by the mitochondria.
authors.affiliation: Departamento de Bioquímica Médica, ICB-CCS, Universidade Federal do Rio de Janeiro-UFRJ, Ilha do Fundão, 21941-590-Rio de Janeiro, Brazil.
authors.forename: Danuza Nogueira
authors.initials: DN
authors.lastname: Moysés
authors.forename: Hector
authors.initials: H
authors.lastname: Barrabin
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D004396:Coloring Agents; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007202:Indicators and Reagents; D007476:Ionophores / Q000494:pharmacology; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology*; D024101:Mitochondrial Proteins; D009550:Nigericin / Q000494:pharmacology; D010088:Oxidoreductases / Q000037:antagonists & inhibitors; D010619:Phenazines; D010940:Plant Proteins; D012402:Rotenone / Q000494:pharmacology*; D012430:Ruthenium Red / Q000494:pharmacology; D012457:Salicylamides / Q000494:pharmacology; D014351:Trypanosomatina / Q000254:growth & development / Q000378:metabolism*; D014475:Uncoupling Agents / Q000494:pharmacology*; D014634:Valinomycin / Q000494:pharmacology; D000099188:Alternative Oxidase
chemical_list: D002118:Calcium; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D004396:Coloring Agents; D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; D007476:Ionophores; D024101:Mitochondrial Proteins; D009550:Nigericin; D010088:Oxidoreductases; D010619:Phenazines; D010940:Plant Proteins; D012402:Rotenone; D012430:Ruthenium Red; D012457:Salicylamides; D014475:Uncoupling Agents; D014634:Valinomycin; D000099188:Alternative Oxidase; C005703:salicylhydroxamic acid; C009195:safranine T