title: Oxidative phosphorylation and rotenone-insensitive malate- and NADH-quinone oxidoreductases in Plasmodium yoelii yoelii mitochondria in situ.
abstract: Respiration, membrane potential, and oxidative phosphorylation of mitochondria of Plasmodium yoelii yoelii trophozoites were assayed in situ after permeabilization with digitonin. ADP induced an oligomycin-sensitive transition from resting to phosphorylating respiration in the presence of oxidizable substrates. A functional respiratory chain was demonstrated. In addition, the ability of the parasite to oxidize exogenous NADH, as well as the insensitivity of respiration to rotenone and its sensitivity to flavone, suggested the presence of an alternative NADH-quinone (NADH-Q) oxidoreductase. Rotenone-insensitive respiration and membrane potential generation in the presence of malate suggested the presence of a malate-quinone oxidoreductase. These results are in agreement with the presence of genes in P. yoelii encoding for proteins with homology to NADH-Q oxidoreductases of bacteria, plant, fungi, and protozoa and malate-quinone oxidoreductases of bacteria. The complete inhibition of respiration by antimycin A and cyanide excluded the presence of an alternative oxidase as described in other parasites. An uncoupling effect of fatty acids was partly reversed by bovine serum albumin and GTP but was unaffected by carboxyatractyloside. These results provide the first biochemical evidence of the presence of an alternative NADH-Q oxidoreductase and a malate-quinone oxidoreductase and confirm the operation of oxidative phosphorylation in malaria parasites.
authors.affiliation: Laboratory of Molecular Parasitology, Department of Pathobiology and Center for Zoonoses Research, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA.
authors.forename: Sergio A
authors.initials: SA
authors.lastname: Uyemura
authors.forename: Shuhong
authors.initials: S
authors.lastname: Luo
authors.forename: Mauricio
authors.initials: M
authors.lastname: Vieira
authors.forename: Silvia N J
authors.initials: SN
authors.lastname: Moreno
authors.forename: Roberto
authors.initials: R
authors.lastname: Docampo
mesh_terms: D000818:Animals; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D042967:Electron Transport Complex I / Q000378:metabolism*; D007700:Kinetics; D008291:Malate Dehydrogenase / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D010085:Oxidative Phosphorylation / Q000187:drug effects*; D010101:Oxygen Consumption / Q000187:drug effects; D010967:Plasmodium yoelii / Q000187:drug effects / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology*
chemical_list: D012402:Rotenone; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D008291:Malate Dehydrogenase; D042967:Electron Transport Complex I