Ubiquinone (coenzyme Q or Q) functions in cells as a redox-active co-enzyme of both mitochondrial and plasma membrane electron transport, as an essential lipid soluble antioxidant, and plays a role in thermogenesis and apoptosis. Dietary Q appears to have beneficial effects in treatment of cardiomyopathies and neuro- and muscle-degenerative diseases. Cells are capable of synthesizing Q, but much remains to be learned about the sites of its synthesis, mechanisms of inter- and intra-cellular transport, and the regulation and enzymology of its biosynthesis. The goals of the proposed research are to characterize the polypeptides of the Q biosynthetic pathway and to define the enzymology of Q biosynthesis. The experimental system takes advantage of eight complementation groups of Q deficient (coq) mutants in the yeast Saccharomyces cerevisiae. The coq mutants provide the basis for the characterization of the Coq polypeptides in both yeast and mammals. Synthetic analogs of Q-intermediates provide reagents that serve both as standards in the isolation and characterization of Q intermediates, and as substrates for in vitro assays of enzyme activities. The intracellular location of the Coq polypeptides will be established, and the interdependence of the Coq polypeptides will be studied in the context of determining whether a multi-subunit complex is required for Q biosynthesis, and where in cells it may function. In vitro assays will be developed to characterize the enzymes in Q biosynthesis, which have been particularly refractory to study, namely the monooxygenase and decarboxylase steps. Human Coq homologs will be tested for their ability to rescue the yeast coq mutants, and Q biosynthesis in bovine and rat heart examined by localization of the Coq polypeptides and enzyme activities. The experimental approach employs a combination of chemistry, genetics and biochemistry to delineate the biosynthetic steps responsible for the production of Q in yeast and mammalian cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM045952-13
Application #
6824040
Study Section
Biochemistry Study Section (BIO)
Program Officer
Ikeda, Richard A
Project Start
1991-04-01
Project End
2006-05-31
Budget Start
2004-12-01
Budget End
2006-05-31
Support Year
13
Fiscal Year
2005
Total Cost
$332,254
Indirect Cost
Name
University of California Los Angeles
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
He, Cuiwen H; Xie, Letian X; Allan, Christopher M et al. (2014) Coenzyme Q supplementation or over-expression of the yeast Coq8 putative kinase stabilizes multi-subunit Coq polypeptide complexes in yeast coq null mutants. Biochim Biophys Acta 1841:630-44
Gasser, David L; Winkler, Cheryl A; Peng, Min et al. (2013) Focal segmental glomerulosclerosis is associated with a PDSS2 haplotype and, independently, with a decreased content of coenzyme Q10. Am J Physiol Renal Physiol 305:F1228-38
Allan, Christopher M; Hill, Shauna; Morvaridi, Susan et al. (2013) A conserved START domain coenzyme Q-binding polypeptide is required for efficient Q biosynthesis, respiratory electron transport, and antioxidant function in Saccharomyces cerevisiae. Biochim Biophys Acta 1831:776-791
Xie, Letian X; Ozeir, Mohammad; Tang, Jeniffer Y et al. (2012) Overexpression of the Coq8 kinase in Saccharomyces cerevisiae coq null mutants allows for accumulation of diagnostic intermediates of the coenzyme Q6 biosynthetic pathway. J Biol Chem 287:23571-81
Rahman, Shamima; Clarke, Catherine F; Hirano, Michio (2012) 176th ENMC International Workshop: diagnosis and treatment of coenzyme Q?? deficiency. Neuromuscul Disord 22:76-86
Hill, Shauna; Lamberson, Connor R; Xu, Libin et al. (2012) Small amounts of isotope-reinforced polyunsaturated fatty acids suppress lipid autoxidation. Free Radic Biol Med 53:893-906
Falk, Marni J; Polyak, Erzsebet; Zhang, Zhe et al. (2011) Probucol ameliorates renal and metabolic sequelae of primary CoQ deficiency in Pdss2 mutant mice. EMBO Mol Med 3:410-27
Clarke, Catherine F (2011) Coq6 hydroxylase: unmasked and bypassed. Chem Biol 18:1069-70
Heeringa, Saskia F; Chernin, Gil; Chaki, Moumita et al. (2011) COQ6 mutations in human patients produce nephrotic syndrome with sensorineural deafness. J Clin Invest 121:2013-24
Xie, Letian X; Hsieh, Edward J; Watanabe, Shota et al. (2011) Expression of the human atypical kinase ADCK3 rescues coenzyme Q biosynthesis and phosphorylation of Coq polypeptides in yeast coq8 mutants. Biochim Biophys Acta 1811:348-60

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