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Coq2p function in the Saccharomyces cerevisiae coenzyme Q biosynthetic pathway
Author(s) -
Marbois Beth Noelle,
Xie Letian,
Shi Yuchen,
Hyman Kyle,
Clarke Catherine F.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1036.2
Subject(s) - mutant , saccharomyces cerevisiae , biochemistry , cofactor , biology , mitochondrion , inner mitochondrial membrane , translation (biology) , respiratory chain , biosynthesis , yeast , enzyme , gene , messenger rna
Respiratory electron transport in the plasma membrane of prokaryotes and in the inner mitochondrial membrane of eukaryotes is supported by the crucial lipid component, ubiquinone (coenzyme Q or Q). Here we further characterize the Coq2 polypeptide, a key resident polypeptide of a complex of Coq polypeptides that is necessary to manufacture Q. One mutant allele of Coq2p and a hemaglutanin tagged Coq2p are described and compared to the wild‐type polypeptide in S. cerevisiae via Western blotting, growth curves and lipid analyses. Although stable levels of Coq2 polypeptide are evident in mitochondria isolated from the coq2‐1 mutant, the strain is incapable of aerobic respiration. We also present biochemical evidence that Coq2p is expressed in two forms, one at 30 kDa and another at 41kDa. Growth on non‐fermentable carbon sources invokes the 41 kDa isoform. We speculate that the 41kDa form is necessary for Q synthesis since it is lacking in the coq2‐1 mutant, and not highly expressed in cell extracts of cells grown in media containing fermentable sugars. We describe the coenzyme Q intermediates present in lipid extracts of the coq2‐1 mutant. Our data demonstrate that Coq2p is essential for Q synthesis. This work was supported by NIH grants GM 45952 and NIA AG 19777.