Escherichia coli K-12 substr. MG1655 Reaction:

Superclasses: Reactions Classified By Conversion TypeSimple ReactionsChemical Reactions
Reactions Classified By SubstrateSmall-Molecule Reactions

EC Number:

Enzymes and Genes:
bifunctional 3-demethylubiquinone-8 3-O-methyltransferase and 2-octaprenyl-6-hydroxyphenol methylaseInferred from experiment: ubiG

In Pathway: ubiquinol-8 biosynthesis (prokaryotic)

Note that this reaction equation differs from the official Enzyme Commission reaction equations for this EC number.

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the direction in which it was curated.

Most BioCyc compounds have been protonated to a reference pH value of 7.3. Please see the PGDB Concepts Guide for more information.

Mass balance status: Balanced.

Enzyme Commission Primary Name: 2-polyprenyl-6-hydroxyphenol methylase

Enzyme Commission Synonyms: ubiG (gene name, ambiguous), ubiG methyltransferase (ambiguous), 2-octaprenyl-6-hydroxyphenol methylase

This is the fifth step in ubiquinone biosynthesis.

Enzyme Commission Summary:
UbiG catalyses both methylation steps in ubiquinone biosynthesis in Escherichia coli. The second methylation is classified as EC (3-demethylubiquinol 3-O-methyltransferase) [Hsu96]. 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 (polyprenyldihydroxybenzoate methyltransferase). The substrate of the eukaryotic enzyme (3,4-dihydroxy-5-all-trans-polyprenylbenzoate) differs by an additional carboxylate moiety.

Citations: [Poon99]

Gene-Reaction Schematic

Gene-Reaction Schematic

Relationship Links: BRENDA:EC:, ENZYME:EC:, IUBMB-ExplorEnz:EC:


Hsu96: Hsu AY, Poon WW, Shepherd JA, Myles DC, Clarke CF (1996). "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;35(30);9797-806. PMID: 8703953

Poon99: Poon WW, Barkovich RJ, Hsu AY, Frankel A, Lee PT, Shepherd JN, Myles DC, Clarke CF (1999). "Yeast and rat Coq3 and Escherichia coli UbiG polypeptides catalyze both O-methyltransferase steps in coenzyme Q biosynthesis." J Biol Chem 274(31);21665-72. PMID: 10419476

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
Page generated by Pathway Tools version 19.5 (software by SRI International) on Thu Nov 26, 2015, biocyc12.