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MetaCyc Enzyme: bifunctional 3-demethylubiquinone-8 3-O-methyltransferase and 2-octaprenyl-6-hydroxyphenol methylase

Gene: ubiG Accession Numbers: EG11143 (MetaCyc), b2232, ECK2224

Synonyms: pufX, yfaB

Species: Escherichia coli K-12 substr. MG1655

Subunit composition of bifunctional 3-demethylubiquinone-8 3-O-methyltransferase and 2-octaprenyl-6-hydroxyphenol methylase = [UbiG]2

Summary:
UbiG is an O-methyltransferase that catalyzes both O-methylation reactions in the biosynthesis of ubiquinone.

The enzyme is mostly cytoplasmic, but also shows some association with the membrane [Leppik76a].

A genetic interaction between ubiX and ubiG was shown, suggesting that UbiX interacts with UbiG [Zeng98, Gulmezian06]. Expression of UbiX can restore the final O-methylation reaction of the ubiquinone biosynthesis pathway in the IS16 mutant strain with the UbiG L132Q mutation [Gulmezian06].

Two leaky ubiG mutants accumulate 2-octaprenylphenol and OMHMB [Stroobant72]. An independently isolated ubiG mutant is unable to grow aerobically on non-fermentable substrates [Wu92d], and ubiG deletion mutants are respiration defective and thus unable to grow on succinate [Hsu96] or glycerol [Joyce06] as the sole source of carbon.

Regulation of ubiG expression has been described [Gibert88].

N-terminally hexahistidine tagged UbiG has been expressed, crystallized, and subjected to preliminary crystallographic studies. The data suggested the presence of one molecule per asymmetric unit in the crystal [Xing11]. Earlier gel filtration data showed an apparent molecular mass of approximately 50 kDa, suggesting a homodimer [Leppik76a].

ubiG, ubiF, ubiX, ubiH, and ubiE mutants from the Keio K-12 mutant collection showed elevated resistance to the broad-spectrum antibiotic D-cycloserine (DCS) when grown in complex media, suggesting that they may be involved in DCS sensitivity [Baisa13].

Reviews: [Meganathan01, Meganathan01a]

Locations: inner membrane, cytosol

Map Position: [2,337,589 -> 2,338,311]

Molecular Weight of Polypeptide: 26.555 kD (from nucleotide sequence)

Molecular Weight of Multimer: 50 kD (experimental) [Leppik76a]

pI: 6.52

Unification Links: ASAP:ABE-0007374 , CGSC:44 , DIP:DIP-11070N , EchoBASE:EB1133 , EcoGene:EG11143 , EcoliWiki:b2232 , Mint:MINT-1254635 , ModBase:P17993 , OU-Microarray:b2232 , PortEco:ubiG , PR:PRO_000024159 , Pride:P17993 , Protein Model Portal:P17993 , RefSeq:NP_416735 , RegulonDB:EG11143 , SMR:P17993 , String:511145.b2232 , UniProt:P17993

Relationship Links: InterPro:IN-FAMILY:IPR010233 , Panther:IN-FAMILY:PTHR23134

Gene-Reaction Schematic: ?

GO Terms:

Biological Process: GO:0006744 - ubiquinone biosynthetic process Inferred from experiment Inferred by computational analysis [UniProtGOA12, UniProtGOA11a, GOA01a, Hsu96]
GO:0032259 - methylation Inferred by computational analysis [UniProtGOA11a]
Molecular Function: GO:0005515 - protein binding Inferred from experiment [Rajagopala14, Butland05]
GO:0043431 - 2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone methyltransferase activity Inferred from experiment [Poon99]
GO:0008168 - methyltransferase activity Inferred by computational analysis [UniProtGOA11a]
GO:0008425 - 2-polyprenyl-6-methoxy-1,4-benzoquinone methyltransferase activity Inferred by computational analysis [GOA01a]
GO:0008689 - 3-demethylubiquinone-9 3-O-methyltransferase activity Inferred by computational analysis [GOA01]
GO:0016740 - transferase activity Inferred by computational analysis [UniProtGOA11a]
Cellular Component: GO:0005829 - cytosol Inferred from experiment Inferred by computational analysis [DiazMejia09, Ishihama08]
GO:0005886 - plasma membrane

MultiFun Terms: metabolism biosynthesis of building blocks cofactors, small molecule carriers menaquinone, ubiquinone
metabolism energy metabolism, carbon aerobic respiration

Credits:
Imported from EcoCyc 16-Sep-2014 by Paley S , SRI International


Enzymatic reaction of: 2-octaprenyl-6-hydroxyphenol methylase

3-(all-trans-octaprenyl)benzene-1,2-diol + S-adenosyl-L-methionine <=> 2-methoxy-6-(all-trans-octaprenyl)phenol + S-adenosyl-L-homocysteine + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

The reaction is physiologically favored in the direction shown.

In Pathways: superpathway of chorismate metabolism , superpathway of ubiquinol-8 biosynthesis (prokaryotic) , ubiquinol-8 biosynthesis (prokaryotic)

Credits:
Imported from EcoCyc 16-Sep-2014 by Paley S , SRI International


Enzymatic reaction of: 3-demethylubiquinone-8 3-O-methyltransferase

Synonyms: 3,4-dihydroxy-5-hexaprenylbenzoate methyltransferase, DHHB 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 3-O-methyltransferase, 3-demethylubiquinone 3-methyltransferase

S-adenosyl-L-methionine + 3-demethylubiquinol-8 <=> S-adenosyl-L-homocysteine + ubiquinol-8 + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

The reaction is physiologically favored in the direction shown.

In Pathways: superpathway of chorismate metabolism , superpathway of ubiquinol-8 biosynthesis (prokaryotic) , ubiquinol-8 biosynthesis (prokaryotic)

Credits:
Imported from EcoCyc 16-Sep-2014 by Paley S , SRI International

Cofactors or Prosthetic Groups: Zn2+ [Comment 1, Leppik76a]

Activators (Unknown Mechanism): dithiothreitol [Leppik76a]

History:
10/20/97 Gene b2232 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG11143; confirmed by SwissProt match.


References

Baisa13: Baisa G, Stabo NJ, Welch RA (2013). "Characterization of Escherichia coli D-cycloserine transport and resistant mutants." J Bacteriol 195(7);1389-99. PMID: 23316042

Butland05: Butland G, Peregrin-Alvarez JM, Li J, Yang W, Yang X, Canadien V, Starostine A, Richards D, Beattie B, Krogan N, Davey M, Parkinson J, Greenblatt J, Emili A (2005). "Interaction network containing conserved and essential protein complexes in Escherichia coli." Nature 433(7025);531-7. PMID: 15690043

DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114

Gibert88: Gibert I, Llagostera M, Barbe J (1988). "Regulation of ubiG gene expression in Escherichia coli." J Bacteriol 170(3);1346-9. PMID: 2830238

GOA01: GOA, MGI (2001). "Gene Ontology annotation based on Enzyme Commission mapping." Genomics 74;121-128.

GOA01a: GOA, DDB, FB, MGI, ZFIN (2001). "Gene Ontology annotation through association of InterPro records with GO terms."

Gulmezian06: Gulmezian M, Zhang H, Javor GT, Clarke CF (2006). "Genetic evidence for an interaction of the UbiG O-methyltransferase with UbiX in Escherichia coli coenzyme Q biosynthesis." J Bacteriol 188(17);6435-9. PMID: 16923914

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

Ishihama08: Ishihama Y, Schmidt T, Rappsilber J, Mann M, Hartl FU, Kerner MJ, Frishman D (2008). "Protein abundance profiling of the Escherichia coli cytosol." BMC Genomics 9;102. PMID: 18304323

Joyce06: Joyce AR, Reed JL, White A, Edwards R, Osterman A, Baba T, Mori H, Lesely SA, Palsson BO, Agarwalla S (2006). "Experimental and computational assessment of conditionally essential genes in Escherichia coli." J Bacteriol 188(23);8259-71. PMID: 17012394

Leppik76a: Leppik RA, Stroobant P, Shineberg B, Young IG, Gibson F (1976). "Membrane-associated reactions in ubiquinone biosynthesis. 2-Octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone methyltransferase." Biochim Biophys Acta 1976;428(1);146-56. PMID: 769831

Meganathan01: Meganathan R (2001). "Ubiquinone biosynthesis in microorganisms." FEMS Microbiol Lett 203(2);131-9. PMID: 11583838

Meganathan01a: Meganathan R (2001). "Biosynthesis of menaquinone (vitamin K2) and ubiquinone (coenzyme Q): a perspective on enzymatic mechanisms." Vitam Horm 61;173-218. PMID: 11153266

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

Rajagopala14: Rajagopala SV, Sikorski P, Kumar A, Mosca R, Vlasblom J, Arnold R, Franca-Koh J, Pakala SB, Phanse S, Ceol A, Hauser R, Siszler G, Wuchty S, Emili A, Babu M, Aloy P, Pieper R, Uetz P (2014). "The binary protein-protein interaction landscape of Escherichia coli." Nat Biotechnol 32(3);285-90. PMID: 24561554

Stroobant72: Stroobant P, Young IG, Gibson F (1972). "Mutants of Escherichia coli K-12 blocked in the final reaction of ubiquinone biosynthesis: characterization and genetic analysis." J Bacteriol 109(1);134-9. PMID: 4333375

UniProtGOA11a: UniProt-GOA (2011). "Gene Ontology annotation based on manual assignment of UniProtKB keywords in UniProtKB/Swiss-Prot entries."

UniProtGOA12: UniProt-GOA (2012). "Gene Ontology annotation based on UniPathway vocabulary mapping."

Wu92d: Wu G, Williams HD, Zamanian M, Gibson F, Poole RK (1992). "Isolation and characterization of Escherichia coli mutants affected in aerobic respiration: the cloning and nucleotide sequence of ubiG. Identification of an S-adenosylmethionine-binding motif in protein, RNA, and small-molecule methyltransferases." J Gen Microbiol 1992;138 ( Pt 10);2101-12. PMID: 1479344

Xing11: Xing L, Zhu Y, Fang P, Wang J, Zeng F, Teng M, Li X (2011). "Crystallization and preliminary crystallographic studies of UbiG, an O-methyltransferase from Escherichia coli." Acta Crystallogr Sect F Struct Biol Cryst Commun 67(Pt 6);727-9. PMID: 21636923

Zeng98: Zeng H, Snavely I, Zamorano P, Javor GT (1998). "Low ubiquinone content in Escherichia coli causes thiol hypersensitivity." J Bacteriol 180(14);3681-5. PMID: 9658014


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Tue Nov 25, 2014, biocyc13.