Publications

• Endogenous synthesis of coenzyme Q in eukaryotes.

  Tran U.C., Clarke C.F.

  Coenzyme Q (Q) functions in the mitochondrial respiratory chain and serves as a lipophilic antioxidant. There is increasing interest in the use of Q as a nutritional supplement. Although, the physiological significance of Q is extensively investigated in eukaryotes, ranging from yeast to human, th ... >> More

  Coenzyme Q (Q) functions in the mitochondrial respiratory chain and serves as a lipophilic antioxidant. There is increasing interest in the use of Q as a nutritional supplement. Although, the physiological significance of Q is extensively investigated in eukaryotes, ranging from yeast to human, the eukaryotic Q biosynthesis pathway is best characterized in the budding yeast Saccharomyces cerevisiae. At least ten genes (COQ1-COQ10) have been shown to be required for Q biosynthesis and function in respiration. This review highlights recent knowledge about the endogenous synthesis of Q in eukaryotes, with emphasis on S. cerevisiae as a model system. << Less

  Mitochondrion 7 Suppl:S62-71(2007) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.

• Functional characterization of OsPPT1, which encodes p-hydroxybenzoate polyprenyltransferase involved in ubiquinone biosynthesis in Oryza sativa.

  Ohara K., Yamamoto K., Hamamoto M., Sasaki K., Yazaki K.

  Prenylation of the aromatic intermediate p-hydroxybenzoate (PHB) is a critical step in ubiquinone (UQ) biosynthesis. The enzyme that catalyzes this prenylation reaction is p-hydroxybenzoate polyprenyltransferase (PPT), which substitutes an aromatic proton at the m-position of PHB with a prenyl cha ... >> More

  Prenylation of the aromatic intermediate p-hydroxybenzoate (PHB) is a critical step in ubiquinone (UQ) biosynthesis. The enzyme that catalyzes this prenylation reaction is p-hydroxybenzoate polyprenyltransferase (PPT), which substitutes an aromatic proton at the m-position of PHB with a prenyl chain provided by polyprenyl diphosphate synthase. The rice genome contains three PPT candidates that share significant similarity with the yeast PPT (COQ2 gene), and the rice gene showing the highest similarity to COQ2 was isolated by reverse transcription-PCR and designated OsPPT1a. The deduced amino acid sequence of OsPPT1a contained a putative mitochondrial sorting signal at the N-terminus and conserved domains for putative substrate-binding sites typical of PPT protein family members. The subcellular localization of OsPPT1a protein was shown to be mainly in mitochondria based on studies using a green fluorescent protein-PPT fusion. A yeast complementation study revealed that OsPPT1a expression successfully recovered the growth defect of the coq2 mutant. A prenyltransferase assay using recombinant protein showed that OsPPT1a accepted prenyl diphosphates of various chain lengths as prenyl donors, whereas it showed strict substrate specificity for the aromatic substrate PHB as a prenyl acceptor. The apparent K (m) values for geranyl diphosphate and PHB were 59.7 and 6.04 microM, respectively. The requirement by OsPPT1a and COQ2 for divalent cations was also studied, with Mg2+ found to produce the highest enzyme activity. Northern analysis showed that OsPPT1a mRNA was accumulated in all tissues of O. sativa. These results suggest that OsPPT1a is a functional PPT involved in UQ biosynthesis in O. sativa. << Less

  Plant Cell Physiol 47:581-590(2006) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Functional conservation of coenzyme Q biosynthetic genes among yeasts, plants, and humans.

  Hayashi K., Ogiyama Y., Yokomi K., Nakagawa T., Kaino T., Kawamukai M.

  Coenzyme Q (CoQ) is an essential factor for aerobic growth and oxidative phosphorylation in the electron transport system. The biosynthetic pathway for CoQ has been proposed mainly from biochemical and genetic analyses of Escherichia coli and Saccharomyces cerevisiae; however, the biosynthetic pat ... >> More

  Coenzyme Q (CoQ) is an essential factor for aerobic growth and oxidative phosphorylation in the electron transport system. The biosynthetic pathway for CoQ has been proposed mainly from biochemical and genetic analyses of Escherichia coli and Saccharomyces cerevisiae; however, the biosynthetic pathway in higher eukaryotes has been explored in only a limited number of studies. We previously reported the roles of several genes involved in CoQ synthesis in the fission yeast Schizosaccharomyces pombe. Here, we expand these findings by identifying ten genes (dps1, dlp1, ppt1, and coq3-9) that are required for CoQ synthesis. CoQ10-deficient S. pombe coq deletion strains were generated and characterized. All mutant fission yeast strains were sensitive to oxidative stress, produced a large amount of sulfide, required an antioxidant to grow on minimal medium, and did not survive at the stationary phase. To compare the biosynthetic pathway of CoQ in fission yeast with that in higher eukaryotes, the ability of CoQ biosynthetic genes from humans and plants (Arabidopsis thaliana) to functionally complement the S. pombe coq deletion strains was determined. With the exception of COQ9, expression of all other human and plant COQ genes recovered CoQ10 production by the fission yeast coq deletion strains, although the addition of a mitochondrial targeting sequence was required for human COQ3 and COQ7, as well as A. thaliana COQ6. In summary, this study describes the functional conservation of CoQ biosynthetic genes between yeasts, humans, and plants. << Less

  PLoS One 9:e99038-e99038(2014) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.