Journal of Biochemistry Advance Access originally published online on December 6, 2008
Journal of Biochemistry 2009 145(2):229-237; doi:10.1093/jb/mvn161
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Mitochondrial Dehydrogenases in the Aerobic Respiratory Chain of the Rodent Malaria Parasite Plasmodium yoelii yoelii
1Department of Biomedical Chemistry, Graduate School of Medicine, the University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033; and 2Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
*To whom correspondence addressed. Tel: +81-3-5841-3526, Fax: +81-3-5841-3444, E-mail: tmogi{at}m.u-tokyo.ac.jp
Correspondence may also be addressed. Tel: +81-3-5841-3526, Fax: +81-3-5841-3444, E-mail: kitak{at}m.u-tokyo.ac.jp
Received October 7, 2008; Accepted November 19, 2008
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Abstract |
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In the intraerythrocytic stages of malaria parasites, mitochondria lack obvious cristae and are assumed to derive energy through glycolysis. For understanding of parasite energy metabolism in mammalian hosts, we isolated rodent malaria mitochondria from Plasmodium yoelii yoelii grown in mice. As potential targets for antiplasmodial agents, we characterized two respiratory dehydrogenases, succinate:ubiquinone reductase (complex II) and alternative NADH dehydrogenase (NDH-II), which is absent in mammalian mitochondria. We found that P. y. yoelii complex II was a four-subunit enzyme and that kinetic properties were similar to those of mammalian enzymes, indicating that the Plasmodium complex II is favourable in catalysing the forward reaction of tricarboxylic acid cycle. Notably, Plasmodium complex II showed IC50 value for atpenin A5 three-order of magnitudes higher than those of mammalian enzymes. Divergence of protist membrane anchor subunits from eukaryotic orthologs likely affects the inhibitor resistance. Kinetic properties and sensitivity to 2-heptyl-4-hydroxyquinoline-N-oxide and aurachin C of NADH: ubiquinone reductase activity of Plasmodium NDH-II were similar to those of plant and fungus enzymes but it can oxidize NADPH and deamino-NADH. Our findings are consistent with the notion that rodent malaria mitochondria are fully capable of oxidative phosphorylation and that these mitochondrial enzymes are potential targets for new antiplasmodials.
Key Words: complex II, inhibitor, mitochondria, NDH-II, rodent malaria
Abbreviations: AC, aurachin C; DCIP, 2,4-dichlorophenolindophenol; DHO, dihydroorotate; DHOD, DHO dehydrogenase; HQNO, 2-heptyl-4-hydroxyquinoline-N-oxide; hrCNE, high-resolution clear-native electrophoresis; IC50, the 50% inhibitory concentration; NBT, nitro blue tetrazolium chloride; NDE, NDH-II bound to the outer surface of the mitochondrial inner membrane; NDI, NDH-II bound to the matrix side of the mitochondrial inner membrane; NQR, NADH:quinone reductase; Qn, ubiquinone-n; SDH, succinate dehydrogenase; SQR, succinate:quinone reductase; TCA, tricarboxylic acid