Journal
BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR AND CELL BIOLOGY OF LIPIDS
Volume 1791, Issue 1, Pages 69-75Publisher
ELSEVIER
DOI: 10.1016/j.bbalip.2008.10.006
Keywords
Saccharomyces cerevisiae; Ubiquinone; Coenzyme Q; Mitochondria; Respiratoty electron transport; Coq4
Funding
- National Institutes of Health [GM45952]
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [R01GM045952] Funding Source: NIH RePORTER
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Coenzyme Q is a redox active lipid essential for aerobic respiration. The Coq4 polypeptide is required for Q biosynthesis and growth on non-fermentable carbon sources, however its exact function in this pathway is not known. Here we probe the functional roles of Coq4p in a yeast Q biosynthetic polypeptide complex. A yeast coq4-1 mutant harboring an E226K substitution is unable to grow on nonfermentable carbon sources. The coq4-1 yeast mutant retains significant Coq3p O-methyltransferase activity, and mitochondria isolated from coq4-1 and coq4-2 (E121K) yeast point mutants contain normal steady state levels of Coq polypeptides, unlike the decreased levels of Coq polypeptides generally found in strains harboring coq gene deletions. Digitonin-solubilized mitochondrial extracts prepared from yeast coq4 point mutants show that Coq3p and Coq4 polypeptides no longer co-migrate as high molecular mass complexes by one- and two-dimensional Blue Native-PAGE. Similarly, gel filtration chromatography confirms that C-methyltransferase activity, Coq3p, Coq4p, and Coq7p migration are disorganized in the coq4-1 mutant mitochondria. The data suggest that Coq4p plays an essential role in organizing a Coq enzyme complex required for Q biosynthesis. (C) 2008 Elsevier B.V. All rights reserved.
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