The Enzyme Database

Your query returned 4 entries.    printer_iconPrintable version



EC 1.14.99.60     
Accepted name: 3-demethoxyubiquinol 3-hydroxylase
Reaction: 6-methoxy-3-methyl-2-(all-trans-polyprenyl)-1,4-benzoquinol + a reduced acceptor + O2 = 3-demethylubiquinol + acceptor + H2O
Glossary: 3-demethylubiquinol = 3-methoxy-6-methyl-5-(all trans-polyprenyl)benzene-1,2,4-triol
Other name(s): 6-methoxy-3-methyl-2-(all-trans-polyprenyl)-1,4-benzoquinol 5-hydroxylase; COQ7 (gene name); clk-1 (gene name); ubiF (gene name)
Systematic name: 6-methoxy-3-methyl-2-(all-trans-polyprenyl)-1,4-benzoquinol,acceptor:oxygen oxidoreductase (5-hydroxylating)
Comments: The enzyme catalyses the last hydroxylation reaction during the biosynthesis of ubiquinone.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Marbois, B.N. and Clarke, C.F. The COQ7 gene encodes a protein in Saccharomyces cerevisiae necessary for ubiquinone biosynthesis. J. Biol. Chem. 271 (1996) 2995–3004. [PMID: 8621692]
2.  Vajo, Z., King, L.M., Jonassen, T., Wilkin, D.J., Ho, N., Munnich, A., Clarke, C.F. and Francomano, C.A. Conservation of the Caenorhabditis elegans timing gene clk-1 from yeast to human: a gene required for ubiquinone biosynthesis with potential implications for aging. Mamm Genome 10 (1999) 1000–1004. [PMID: 10501970]
3.  Kwon, O., Kotsakis, A. and Meganathan, R. Ubiquinone (coenzyme Q) biosynthesis in Escherichia coli: identification of the ubiF gene. FEMS Microbiol. Lett. 186 (2000) 157–161. [PMID: 10802164]
4.  Stenmark, P., Grunler, J., Mattsson, J., Sindelar, P.J., Nordlund, P. and Berthold, D.A. A new member of the family of di-iron carboxylate proteins. Coq7 (clk-1), a membrane-bound hydroxylase involved in ubiquinone biosynthesis. J. Biol. Chem. 276 (2001) 33297–33300. [PMID: 11435415]
5.  Tran, U.C., Marbois, B., Gin, P., Gulmezian, M., Jonassen, T. and Clarke, C.F. Complementation of Saccharomyces cerevisiae coq7 mutants by mitochondrial targeting of the Escherichia coli UbiF polypeptide: two functions of yeast Coq7 polypeptide in coenzyme Q biosynthesis. J. Biol. Chem. 281 (2006) 16401–16409. [PMID: 16624818]
[EC 1.14.99.60 created 2018]
 
 
EC 2.1.1.64     
Accepted name: 3-demethylubiquinol 3-O-methyltransferase
Reaction: S-adenosyl-L-methionine + 3-demethylubiquinol-n = S-adenosyl-L-homocysteine + ubiquinol-n
For diagram of ubiquinol biosynthesis, click here
Glossary: 3-demethylubiquinol-n = 3-hydroxy-2-methoxy-5-methyl-6-(all-trans-polyprenyl)-1,4-benzoquinol
Other name(s): 5-demethylubiquinone-9 methyltransferase; OMHMB-methyltransferase; 2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone methyltransferase; S-adenosyl-L-methionine:2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone-O-methyltransferase; COQ3 (gene name); Coq3 O-methyltransferase; 3-demethylubiquinone-9 3-methyltransferase; ubiG (gene name, ambiguous)
Systematic name: S-adenosyl-L-methionine:3-hydroxy-2-methoxy-5-methyl-6-(all-trans-polyprenyl)-1,4-benzoquinol 3-O-methyltransferase
Comments: This enzyme is involved in ubiquinone biosynthesis. Ubiquinones from different organisms have a different number of prenyl units (for example, ubiquinone-6 in Saccharomyces, ubiquinone-9 in rat and ubiquinone-10 in human), and thus the natural substrate for the enzymes from different organisms has a different number of prenyl units. However, the enzyme usually shows a low degree of specificity regarding the number of prenyl units. For example, the human COQ3 enzyme can restore biosynthesis of ubiquinone-6 in coq3 deletion mutants of yeast [3]. The enzymes from yeast, Escherichia coli and rat also catalyse the methylation of 3,4-dihydroxy-5-all-trans-polyprenylbenzoate [3] (a reaction that is classified as EC 2.1.1.114, polyprenyldihydroxybenzoate methyltransferase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 63774-48-1
References:
1.  Houser, R.M. and Olson, R.E. 5-Demethylubiquinone-9-methyltransferase from rat liver mitochondria. Characterization, localization, and solubilization. J. Biol. Chem. 252 (1977) 4017–4021. [PMID: 863914]
2.  Leppik, R.A., Stroobant, P., Shineberg, B., Young, I.G. and Gibson, F. Membrane-associated reactions in ubiquinone biosynthesis. 2-Octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone methyltransferase. Biochim. Biophys. Acta 428 (1976) 146–156. [DOI] [PMID: 769831]
3.  Poon, W.W., Barkovich, R.J., Hsu, A.Y., Frankel, A., Lee, P.T., Shepherd, J.N., Myles, D.C. and Clarke, C.F. Yeast and rat Coq3 and Escherichia coli UbiG polypeptides catalyze both O-methyltransferase steps in coenzyme Q biosynthesis. J. Biol. Chem. 274 (1999) 21665–21672. [DOI] [PMID: 10419476]
4.  Jonassen, T. and Clarke, C.F. Isolation and functional expression of human COQ3, a gene encoding a methyltransferase required for ubiquinone biosynthesis. J. Biol. Chem. 275 (2000) 12381–12387. [DOI] [PMID: 10777520]
[EC 2.1.1.64 created 1982, modified 2011]
 
 
EC 2.1.1.114     
Accepted name: polyprenyldihydroxybenzoate methyltransferase
Reaction: S-adenosyl-L-methionine + 3,4-dihydroxy-5-all-trans-polyprenylbenzoate = S-adenosyl-L-homocysteine + 3-methoxy-4-hydroxy-5-all-trans-polyprenylbenzoate
For diagram of ubiquinol biosynthesis, click here
Other name(s): 3,4-dihydroxy-5-hexaprenylbenzoate methyltransferase; dihydroxyhexaprenylbenzoate methyltransferase; COQ3 (gene name); Coq3 O-methyltransferase; DHHB O-methyltransferase
Systematic name: S-adenosyl-L-methionine:3,4-dihydroxy-5-all-trans-polyprenylbenzoate 3-O-methyltransferase
Comments: This enzyme is involved in ubiquinone biosynthesis. Ubiquinones from different organisms have a different number of prenyl units (for example, ubiquinone-6 in Saccharomyces, ubiquinone-9 in rat and ubiquinone-10 in human), and thus the natural substrate for the enzymes from different organisms has a different number of prenyl units. However, the enzyme usually shows a low degree of specificity regarding the number of prenyl units. For example, the human COQ3 enzyme can restore biosynthesis of ubiquinone-6 in coq3 deletion mutants of yeast [3]. The enzymes from yeast and rat also catalyse the methylation of 3-demethylubiquinol-6 and 3-demethylubiquinol-9, respectively [2] (this activity is classified as EC 2.1.1.64, 3-demethylubiquinol 3-O-methyltransferase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 139569-31-6
References:
1.  Clarke, C.F., Williams, W., Teruya, J.H. Ubiquinone biosynthesis in Saccharomyces cerevisiae. Isolation and sequence of COQ3, the 3,4-dihydroxy-5-hexaprenylbenzoate methyltransferase gene. J. Biol. Chem. 266 (1991) 16636–16641. [PMID: 1885593]
2.  Poon, W.W., Barkovich, R.J., Hsu, A.Y., Frankel, A., Lee, P.T., Shepherd, J.N., Myles, D.C. and Clarke, C.F. Yeast and rat Coq3 and Escherichia coli UbiG polypeptides catalyze both O-methyltransferase steps in coenzyme Q biosynthesis. J. Biol. Chem. 274 (1999) 21665–21672. [DOI] [PMID: 10419476]
3.  Jonassen, T. and Clarke, C.F. Isolation and functional expression of human COQ3, a gene encoding a methyltransferase required for ubiquinone biosynthesis. J. Biol. Chem. 275 (2000) 12381–12387. [DOI] [PMID: 10777520]
4.  Xing, L., Zhu, Y., Fang, P., Wang, J., Zeng, F., Li, X., Teng, M. and Li, X. Crystallization and preliminary crystallographic studies of UbiG, an O-methyltransferase from Escherichia coli. Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 67 (2011) 727–729. [DOI] [PMID: 21636923]
[EC 2.1.1.114 created 1999]
 
 
EC 2.1.1.222     
Accepted name: 2-polyprenyl-6-hydroxyphenol methylase
Reaction: S-adenosyl-L-methionine + 3-(all-trans-polyprenyl)benzene-1,2-diol = S-adenosyl-L-homocysteine + 2-methoxy-6-(all-trans-polyprenyl)phenol
For diagram of ubiquinol biosynthesis, click here
Other name(s): ubiG (gene name, ambiguous); ubiG methyltransferase (ambiguous); 2-octaprenyl-6-hydroxyphenol methylase
Systematic name: S-adenosyl-L-methionine:3-(all-trans-polyprenyl)benzene-1,2-diol 2-O-methyltransferase
Comments: UbiG catalyses both methylation steps in ubiquinone biosynthesis in Escherichia coli. The second methylation is classified as EC 2.1.1.64 (3-demethylubiquinol 3-O-methyltransferase) [2]. In eukaryotes Coq3 catalyses the two methylation steps in ubiquinone biosynthesis. However, while the second methylation is common to both enzymes, the first methylation by Coq3 occurs at a different position within the pathway, and thus involves a different substrate and is classified as EC 2.1.1.114 (polyprenyldihydroxybenzoate methyltransferase). The substrate of the eukaryotic enzyme (3,4-dihydroxy-5-all-trans-polyprenylbenzoate) differs by an additional carboxylate moiety.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Poon, W.W., Barkovich, R.J., Hsu, A.Y., Frankel, A., Lee, P.T., Shepherd, J.N., Myles, D.C. and Clarke, C.F. Yeast and rat Coq3 and Escherichia coli UbiG polypeptides catalyze both O-methyltransferase steps in coenzyme Q biosynthesis. J. Biol. Chem. 274 (1999) 21665–21672. [DOI] [PMID: 10419476]
2.  Hsu, A.Y., Poon, W.W., Shepherd, J.A., Myles, D.C. and Clarke, C.F. 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 35 (1996) 9797–9806. [DOI] [PMID: 8703953]
[EC 2.1.1.222 created 2011, modified 2013]
 
 


Data © 2001–2020 IUBMB
Web site © 2005–2020 Andrew McDonald