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Pathway Description

Ubiquinone Biosynthesis

Saccharomyces cerevisiae

Metabolic Pathway

Ubiquinone is also known as coenzyme Q10. It is a 1,4-benzoquinone, where Q refers to the quinone chemical group, and 10 refers to the isoprenyl chemical subunits. Ubiquinone is a carrier of hydrogen atoms (protons plus electrons) and functions as an ubiquitous coenzyme in redox reactions, where it is first reduced to the enzyme-bound intermediate radical semiquinone and in a second reduction to ubiquinol (Dihydroquinone; CoQH2). Ubiquinone is not tightly bound or covalently linked to any known protein complex but is very mobile. In eukaryotes ubiquinones were found in the inner mito-chondrial membrane and in other membranes such as the endoplasmic reticulum, Golgi vesicles, lysosomes and peroxisomes. The benzoquinone portion of Coenzyme Q10 is synthesized from tyrosine, whereas the isoprene sidechain is synthesized from acetyl-CoA through the mevalonate pathway. The mevalonate pathway is also used for the first steps of cholesterol biosynthesis. The enzyme para-hydroxybenzoate polyprenyltransferase catalyzes the condensation of p-hydroxybenzoate with polyprenyl diphosphate to generate ubiquinone.

References

Ubiquinone Biosynthesis References

Ashby MN, Edwards PA: Elucidation of the deficiency in two yeast coenzyme Q mutants. Characterization of the structural gene encoding hexaprenyl pyrophosphate synthetase. J Biol Chem. 1990 Aug 5;265(22):13157-64.

Pubmed: 2198286

Baba SW, Belogrudov GI, Lee JC, Lee PT, Strahan J, Shepherd JN, Clarke CF: Yeast Coq5 C-methyltransferase is required for stability of other polypeptides involved in coenzyme Q biosynthesis. J Biol Chem. 2004 Mar 12;279(11):10052-9. doi: 10.1074/jbc.M313712200. Epub 2003 Dec 29.

Pubmed: 14701817

Belogrudov GI, Lee PT, Jonassen T, Hsu AY, Gin P, Clarke CF: Yeast COQ4 encodes a mitochondrial protein required for coenzyme Q synthesis. Arch Biochem Biophys. 2001 Aug 1;392(1):48-58. doi: 10.1006/abbi.2001.2448.

Pubmed: 11469793

Casey J, Threlfall DR: Synthesis of 5-demethoxyubiquinone-6 and ubiquinone-6 from 3-hexaprenyl-4-hydroxybenzoate in yeast mitochondria. FEBS Lett. 1978 Jan 15;85(2):249-53.

Pubmed: 620805

Dibrov E, Robinson KM, Lemire BD: The COQ5 gene encodes a yeast mitochondrial protein necessary for ubiquinone biosynthesis and the assembly of the respiratory chain. J Biol Chem. 1997 Apr 4;272(14):9175-81.

Pubmed: 9083048

Hsieh EJ, Gin P, Gulmezian M, Tran UC, Saiki R, Marbois BN, Clarke CF: Saccharomyces cerevisiae Coq9 polypeptide is a subunit of the mitochondrial coenzyme Q biosynthetic complex. Arch Biochem Biophys. 2007 Jul 1;463(1):19-26. doi: 10.1016/j.abb.2007.02.016. Epub 2007 Mar 8.

Pubmed: 17391640

Hsu AY, Poon WW, Shepherd JA, Myles DC, Clarke CF: Complementation of coq3 mutant yeast by mitochondrial targeting of the Escherichia coli UbiG polypeptide: evidence that UbiG catalyzes both O-methylation steps in ubiquinone biosynthesis. Biochemistry. 1996 Jul 30;35(30):9797-806. doi: 10.1021/bi9602932.

Pubmed: 8703953

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Visualize Compound Data

		2-Hexaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone
		2-Hexaprenyl-3-methyl-6-methoxy-1,4 benzoquinone
		2-Hexaprenyl-6-methoxy-1,4-benzoquinone
		2-Hexaprenyl-6-methoxyphenol
		3-Hexaprenyl-4,5-Dihydroxybenzoic acid
		3-Hexaprenyl-4-hydroxy-5-methoxybenzoic acid
		3-Hexaprenyl-4-hydroxybenzoic acid
		4-Hydroxybenzoic acid
		All-trans-hexaprenyl diphosphate
		Fe3+
		Hydrogen Ion
		NADP
		NADPH
		Oxygen
		Pyrophosphate
		S-Adenosylhomocysteine
		S-Adenosylmethionine
		Ubiquinone-6
		Water

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