ubiquinone and pyrimidine

Comparison of the genomes of free-living Bodo saltans and those of parasitic trypanosomatids reveals that the transition from a free-living to a parasitic life style has resulted in the loss of approximately 50% of protein-coding genes. Despite this dramatic reduction in genome size, B. saltans and trypanosomatids still share a significant number of common metabolic traits: glycosomes; a unique set of the pyrimidine biosynthetic pathway genes; an ATP-PFK which is homologous to the bacterial PPi -PFKs rather than to the canonical eukaryotic ATP-PFKs; an alternative oxidase; three phosphoglycerate kinases and two GAPDH isoenzymes; a pyruvate kinase regulated by fructose-2,6-bisphosphate; trypanothione as a substitute for glutathione; synthesis of fatty acids via a unique set of elongase enzymes; and a mitochondrial acetate:succinate coenzyme A transferase. B. saltans has lost the capacity to synthesize ubiquinone. Among genes that are present in B. saltans and lost in all trypanosomatids are those involved in the degradation of mureine, tryptophan and lysine. Novel acquisitions of trypanosomatids are components of pentose sugar metabolism, pteridine reductase and bromodomain-factor proteins. In addition, only the subfamily Leishmaniinae has acquired a gene for catalase and the capacity to convert diaminopimelic acid to lysine.

Topics: Amino Acids; Bacteria; Carbohydrate Metabolism; Coenzymes; Dolichols; Ergosterol; Eukaryota; Folic Acid; Genes, Protozoan; Gluconeogenesis; Glycolysis; Kinetoplastida; Lipid Metabolism; Mevalonic Acid; Microbodies; Mitochondria; Oxidoreductases; Pentose Phosphate Pathway; Peroxisomes; Phospholipids; Polyamines; Protein Prenylation; Protozoan Proteins; Purines; Pyrimidines; Reactive Oxygen Species; Trypanosomatina; Ubiquinone; Urea; Vitamins

To explore the effects of depression on cardiac autonomic nerve function and related metabolic pathways, the heart rate variability (HRV) and urinary differential metabolites were detected on the college students with depression.. 12 female freshmen with depression were filtered by the Beck Depression Inventory (BDI-II) and Self-rating Depression Scale (SDS). By wearing an HRV monitoring system, time domain indexes and frequency domain indexes were measured over 24 hours. Liquid chromatography-mass spectrometry (LC-MS) was used to detect their urinary differential metabolites. Differential metabolites were identified by principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA). The metabolic pathways related to these differential metabolites were analyzed by the MetPA database.. Stress time was significantly increased, and recovery time was markedly decreased in the depression group compared with the control group (. Some autonomic nervous system disruption, high stress, and poor fatigue recovery were confirmed in college students with depression. The metabolic mechanism involved the disruption of coenzyme Q biosynthesis, glycine-serine-threonine metabolism, tyrosine metabolism, pyrimidine metabolism, and steroid metabolism under daily stress.

Topics: Adolescent; Autonomic Nervous System; Depression; Fatigue; Female; Glycine; Heart Rate; Humans; Metabolomics; Monitoring, Physiologic; Pyrimidines; Serine; Steroids; Stress, Physiological; Students; Threonine; Tyrosine; Ubiquinone; Urine; Young Adult

Cancer cells without mitochondrial DNA (mtDNA) do not form tumors unless they reconstitute oxidative phosphorylation (OXPHOS) by mitochondria acquired from host stroma. To understand why functional respiration is crucial for tumorigenesis, we used time-resolved analysis of tumor formation by mtDNA-depleted cells and genetic manipulations of OXPHOS. We show that pyrimidine biosynthesis dependent on respiration-linked dihydroorotate dehydrogenase (DHODH) is required to overcome cell-cycle arrest, while mitochondrial ATP generation is dispensable for tumorigenesis. Latent DHODH in mtDNA-deficient cells is fully activated with restoration of complex III/IV activity and coenzyme Q redox-cycling after mitochondrial transfer, or by introduction of an alternative oxidase. Further, deletion of DHODH interferes with tumor formation in cells with fully functional OXPHOS, while disruption of mitochondrial ATP synthase has little effect. Our results show that DHODH-driven pyrimidine biosynthesis is an essential pathway linking respiration to tumorigenesis, pointing to inhibitors of DHODH as potential anti-cancer agents.

Topics: Animals; Cell Line, Tumor; Cell Respiration; Dihydroorotate Dehydrogenase; DNA, Mitochondrial; Humans; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mitochondria; Neoplasms; Oxidative Phosphorylation; Oxidoreductases Acting on CH-CH Group Donors; Pyrimidines; Ubiquinone

Primary disorders of the human coenzyme Q

Topics: Animals; Apoptosis; Ataxia; Biosynthetic Pathways; Cytochrome P-450 Enzyme System; Disease Models, Animal; Humans; Hydroxybenzoates; Mice; Mitochondria; Mitochondrial Diseases; Muscle Weakness; Pyrimidines; Solubility; Treatment Outcome; Ubiquinone; Vitamins

Some mutations of the DHODH (dihydro-orotate dehydrogenase) gene lead to postaxial acrofacial dysostosis or Miller syndrome. Only DHODH is localized at mitochondria among enzymes of the de novo pyrimidine biosynthesis pathway. Since the pyrimidine biosynthesis pathway is coupled to the mitochondrial RC (respiratory chain) via DHODH, impairment of DHODH should affect the RC function. To investigate this, we used siRNA (small interfering RNA)-mediated knockdown and observed that DHODH knockdown induced cell growth retardation because of G₂/M cell-cycle arrest, whereas pyrimidine deficiency usually causes G₁/S arrest. Inconsistent with this, the cell retardation was not rescued by exogenous uridine, which should bypass the DHODH reaction for pyrimidine synthesis. DHODH depletion partially inhibited the RC complex III, decreased the mitochondrial membrane potential, and increased the generation of ROS (reactive oxygen species). We observed that DHODH physically interacts with respiratory complexes II and III by IP (immunoprecipitation) and BN (blue native)/SDS/PAGE analysis. Considering that pyrimidine deficiency alone does not induce craniofacial dysmorphism, the DHODH mutations may contribute to the Miller syndrome in part through somehow altered mitochondrial function.

Topics: Abnormalities, Multiple; Dihydroorotate Dehydrogenase; Electron Transport Complex II; HeLa Cells; Humans; Limb Deformities, Congenital; Mandibulofacial Dysostosis; Membrane Potential, Mitochondrial; Micrognathism; Mitochondria; Mutation; Oxidative Phosphorylation; Oxidoreductases Acting on CH-CH Group Donors; Pyrimidines; Reactive Oxygen Species; RNA, Small Interfering; Ubiquinone

Coenzyme Q(10) (CoQ(10)) deficiency has been associated with an increasing number of clinical phenotypes that respond to CoQ(10) supplementation. In two siblings with encephalomyopathy, nephropathy and severe CoQ(10) deficiency, a homozygous mutation was identified in the CoQ(10) biosynthesis gene COQ2, encoding polyprenyl-pHB transferase. To confirm the pathogenicity of this mutation, we have demonstrated that human wild-type, but not mutant COQ2, functionally complements COQ2 defective yeast. In addition, an equivalent mutation introduced in the yeast COQ2 gene also decreases both CoQ(6) concentration and growth in respiratory-chain dependent medium. Polyprenyl-pHB transferase activity was 33-45% of controls in COQ2 mutant fibroblasts. CoQ-dependent mitochondrial complexes activities were restored in deficient fibroblasts by CoQ(10) supplementation, and growth rate was restored in these cells by either CoQ(10) or uridine supplementation. This work is the first direct demonstration of the pathogenicity of a COQ2 mutation involved in human disease, and establishes yeast as a useful model to study human CoQ(10) deficiency. Moreover, we demonstrate that CoQ(10) deficiency in addition to the bioenergetics defect also impairs de novo pyrimidine synthesis, which may contribute to the pathogenesis of the disease.

Topics: Alkyl and Aryl Transferases; Amino Acid Sequence; Base Sequence; Cell Division; Cells, Cultured; Coenzymes; Energy Metabolism; Enzyme Activation; Fibroblasts; Genetic Complementation Test; HeLa Cells; Humans; Immunoblotting; Mitochondria; Molecular Sequence Data; Mutation, Missense; Prohibitins; Pyrimidines; Saccharomyces cerevisiae; Sequence Alignment; Ubiquinone; Uridine