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Aconitase catalyzes the conversion of citrate to isocitrate in the tricarboxylic acid (TCA) cycle, and its deficiency in humans is associated with an infantile neurodegenerative disorder affecting mainly the cerebellum and retina. Here we investigated the effect of gene knockout and knockdown of the mitochondrial aconitase Acon in Drosophila. Acon-knockout flies were homozygous lethal, indicating that Acon is essential for viability. RNA interference-generated Acon-knockdown flies exhibited a variety of phenotypes, such as reduced locomotor activity, a shortened lifespan, and increased cell death in the developing brain. Metabolomic analysis revealed that acetyl-CoA, citrate/isocitrate, and cis-aconitate were significantly increased, while most metabolites of glycolysis and the TCA cycle were reduced. Reduced triacylglyceride and increased acetyl-CoA suggested that lipids were used as an energy source because of the impaired glycolysis and TCA cycle. The Acon-knockdown model should facilitate further understanding of the pathophysiology of m-aconitase deficiency in humans.

Mitochondrial trifunctional protein (MTP), which consists of the MTPα and MTPβ subunits, catalyzes long-chain fatty acid β-oxidation. MTP deficiency in humans results in Reye-like syndrome. Here, we generated Drosophila models of MTP deficiency by targeting two genes encoding Drosophila homologs of human MTPα and MTPβ, respectively. Both Mtpα(KO) and Mtpβ(KO) flies were viable, but demonstrated reduced lifespan, defective locomotor activity, and reduced fecundity represented by the number of eggs laid by the females. The phenotypes of Mtpα(KO) flies were generally more striking than those of Mtpβ(KO) flies. Mtpα(KO) flies were hypersensitive to fasting, and retained lipid droplets in their fat body cells as in non-fasting conditions. The amount of triglyceride was also unchanged upon fasting in Mtpα(KO) flies, suggesting that lipid mobilization was disrupted. Finally, we showed that both Mtpα(KO) and Mtpβ(KO) flies accumulated acylcarnitine and hydroxyacylcarnitine, diagnostic markers of MTP deficiencies in humans. Our results indicated that both Mtpα(KO) and Mtpβ(KO) flies were impaired in long-chain fatty acid β-oxidation. These flies should be useful as a model system to investigate the molecular pathogenesis of MTP deficiency.