Reaction: S-adenosyl-L-methionine + 2-methoxy-6-all-trans-polyprenyl-1,4-benzoquinol = S-adenosyl-L-homocysteine + 6-methoxy-3-methyl-2-all-trans-polyprenyl-1,4-benzoquinol
For diagram of reaction click here.
Other name(s): ubiE (gene name, ambiguous)
Systematic name: S-adenosyl-L-methionine:2-methoxy-6-all-trans-polyprenyl-1,4-benzoquinol 5-C-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, when the COQ5 gene from Saccharomyces cerevisiae is introduced into Escherichia coli, it complements the respiratory deficiency of an ubiE mutant . The bifunctional enzyme from Escherichia coli also catalyses the methylation of demethylmenaquinol-8 (this activity is classified as EC 126.96.36.199) .
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:
1. Lee, P.T., Hsu, A.Y., Ha, H.T. and Clarke, C.F. A C-methyltransferase involved in both ubiquinone and menaquinone biosynthesis: isolation and identification of the Escherichia coli ubiE gene. J. Bacteriol. 179 (1997) 1748-1754. [PMID: 9045837]
2. Young, I.G., McCann, L.M., Stroobant, P. and Gibson, F. Characterization and genetic analysis of mutant strains of Escherichia coli K-12 accumulating the biquinone precursors 2-octaprenyl-6-methoxy-1,4-benzoquinone and 2-octaprenyl-3-methyl-6-methoxy-1,4-benzoquinone. J. Bacteriol. 105 (1971) 769-778. [PMID: 4323297]
3. Dibrov, E., Robinson, K.M. and Lemire, B.D. The COQ5 gene encodes a yeast mitochondrial protein necessary for ubiquinone biosynthesis and the assembly of the respiratory chain. J. Biol. Chem. 272 (1997) 9175-9181. [PMID: 9083048]
4. Barkovich, R.J., Shtanko, A., Shepherd, J.A., Lee, P.T., Myles, D.C., Tzagoloff, A. and Clarke, C.F. Characterization of the COQ5 gene from Saccharomyces cerevisiae. Evidence for a C-methyltransferase in ubiquinone biosynthesis. J. Biol. Chem. 272 (1997) 9182-9188. [PMID: 9083049]