Escherichia coli K-12 substr. MG1655 Enzyme: galactoside O-acetyltransferase

Gene: lacA Accession Numbers: EG10524 (EcoCyc), b0342, ECK0339

Synonyms: thiogalactoside acetyltransferase

Regulation Summary Diagram: ?

Regulation summary diagram for lacA

Subunit composition of galactoside O-acetyltransferase = [LacA]3
         galactoside O-acetyltransferase monomer = LacA

Early work done on the protein identified it as a homodimer, however recent work has shown it to be a homotrimer. [Lewendon95]

Review: [Roderick05]

Gene Citations: [Zaslaver06, Murakawa91, McCormick91]

Locations: cytosol

Map Position: [360,473 <- 361,084] (7.77 centisomes, 28°)
Length: 612 bp / 203 aa

Molecular Weight of Polypeptide: 22.799 kD (from nucleotide sequence)

pI: 6.65

Unification Links: ASAP:ABE-0001177 , CGSC:579 , DIP:DIP-10078N , EchoBASE:EB0519 , EcoGene:EG10524 , EcoliWiki:b0342 , ModBase:P07464 , OU-Microarray:b0342 , PortEco:lacA , PR:PRO_000023069 , Protein Model Portal:P07464 , RefSeq:NP_414876 , RegulonDB:EG10524 , SMR:P07464 , String:511145.b0342 , UniProt:P07464

Relationship Links: InterPro:IN-FAMILY:IPR001451 , InterPro:IN-FAMILY:IPR011004 , InterPro:IN-FAMILY:IPR018357 , InterPro:IN-FAMILY:IPR024688 , PDB:Structure:1KQA , PDB:Structure:1KRR , PDB:Structure:1KRU , PDB:Structure:1KRV , Pfam:IN-FAMILY:PF00132 , Pfam:IN-FAMILY:PF12464 , Prosite:IN-FAMILY:PS00101

In Paralogous Gene Group: 11 (13 members)

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Genetic Regulation Schematic: ?

Genetic regulation schematic for lacA

GO Terms:

Biological Process: GO:0005989 - lactose biosynthetic process Inferred by computational analysis [UniProtGOA11a]
Molecular Function: GO:0008870 - galactoside O-acetyltransferase activity Inferred from experiment Inferred by computational analysis [GOA01, Lewendon95]
GO:0016407 - acetyltransferase activity Inferred by computational analysis [GOA01a]
GO:0016740 - transferase activity Inferred by computational analysis [UniProtGOA11a, GOA01a]
GO:0016746 - transferase activity, transferring acyl groups Inferred by computational analysis [UniProtGOA11a]
Cellular Component: GO:0005737 - cytoplasm Inferred by computational analysis [UniProtGOA11, UniProtGOA11a]
GO:0005829 - cytosol Inferred by computational analysis [DiazMejia09]

MultiFun Terms: metabolism carbon utilization carbon compounds

Essentiality data for lacA knockouts: ?

Growth Medium Growth? T (°C) O2 pH Osm/L Growth Observations
LB enriched Yes 37 Aerobic 6.95   Yes [Gerdes03, Comment 1]
LB Lennox Yes 37 Aerobic 7   Yes [Baba06, Comment 2]
M9 medium with 1% glycerol Yes 37 Aerobic 7.2 0.35 Yes [Joyce06, Comment 3]
MOPS medium with 0.4% glucose Yes 37 Aerobic 7.2 0.22 Yes [Baba06, Comment 2]

Enzymatic reaction of: galactoside O-acetyltransferase

Synonyms: thiogalactoside acetyltransferase, GAT, thiogalactoside transacetylase, acetyl-CoA:β-D-galactoside 6-acetyltransferase, galactosidase acetyltransferase

EC Number:

a β-D-galactoside + acetyl-CoA <=> a 6-acetyl-β-D-galactoside + coenzyme A

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

This reaction is reversible.

Galactoside O-acetyltransferase transfers an acetyl group from acetyl-CoA to the 6-hydroxyl of some galactopyranosides. The enzyme has broad substrate specificity as it will acetylate galactosides, including thiogalactosides, glucosides and lactosides. Its exact physiological function is uncertain, but it may act as a detoxifying enzyme, acetylating non-metabolizable sugars to prevent their re-entry into the cell. [Lewendon95] The enzyme has been crystallized. [Zabin63]

Inhibitors (Competitive): coenzyme A [Musso73]

Inhibitors (Unknown Mechanism): MnSO4 [Musso73, Comment 4] , o-phenanthroline [Musso73, Comment 5] , 1,10-phenanthroline N10-oxide [Musso73] , isopropyl 6-O-acetyl-β-D-thiogalactopyranoside [Musso73, Comment 6]

Kinetic Parameters:

Km (μM)
45.0, 49.0
[Fried80, BRENDA14]
[Musso73, BRENDA14]
59.0, 65.0, 82.0, 104.0, 266.0
[Lewendon95, BRENDA14]

pH(opt): 7 [BRENDA14, ZABIN62], 8.2 [BRENDA14, ZABIN62]

Gene Local Context (not to scale): ?

Gene local context diagram

Transcription Units:

Transcription-unit diagram

Transcription-unit diagram

Transcription-unit diagram

Transcription-unit diagram

Transcription-unit diagram


10/20/97 Gene b0342 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10524; confirmed by SwissProt match.


Baba06: Baba T, Ara T, Hasegawa M, Takai Y, Okumura Y, Baba M, Datsenko KA, Tomita M, Wanner BL, Mori H (2006). "Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection." Mol Syst Biol 2;2006.0008. PMID: 16738554

BRENDA14: BRENDA team (2014). "Imported from BRENDA version existing on Aug 2014."

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

Fried80: Fried VA (1980). "lac Thiogalactoside transacetylase of Escherichia coli K-12 and ML." J Bacteriol 143(1);506-9. PMID: 6995445

Gerdes03: Gerdes SY, Scholle MD, Campbell JW, Balazsi G, Ravasz E, Daugherty MD, Somera AL, Kyrpides NC, Anderson I, Gelfand MS, Bhattacharya A, Kapatral V, D'Souza M, Baev MV, Grechkin Y, Mseeh F, Fonstein MY, Overbeek R, Barabasi AL, Oltvai ZN, Osterman AL (2003). "Experimental determination and system level analysis of essential genes in Escherichia coli MG1655." J Bacteriol 185(19);5673-84. PMID: 13129938

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."

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

Lewendon95: Lewendon A, Ellis J, Shaw WV (1995). "Structural and mechanistic studies of galactoside acetyltransferase, the Escherichia coli LacA gene product." J Biol Chem 1995;270(44);26326-31. PMID: 7592843

McCormick91: McCormick JR, Zengel JM, Lindahl L (1991). "Intermediates in the degradation of mRNA from the lactose operon of Escherichia coli." Nucleic Acids Res 1991;19(10);2767-76. PMID: 1710346

Murakawa91: Murakawa GJ, Kwan C, Yamashita J, Nierlich DP (1991). "Transcription and decay of the lac messenger: role of an intergenic terminator." J Bacteriol 1991;173(1);28-36. PMID: 1702782

Musso73: Musso RE, Zabin I (1973). "Substrate specificity and kinetic studies on thiogalactoside transacetylase." Biochemistry 1973;12(3);553-7. PMID: 4630409

Roderick05: Roderick SL (2005). "The lac operon galactoside acetyltransferase." C R Biol 328(6);568-75. PMID: 15950163

UniProtGOA11: UniProt-GOA (2011). "Gene Ontology annotation based on the manual assignment of UniProtKB Subcellular Location terms in UniProtKB/Swiss-Prot entries."

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

ZABIN62: ZABIN I, KEPES A, MONOD J (1962). "Thiogalactoside transacetylase." J Biol Chem 237;253-7. PMID: 14009486

Zabin63: Zabin I (1963). "Crystalline Thiogalactoside Transacetylase." J Biol Chem 1963;238(10):3300-6. PMID: 14085376

Zaslaver06: Zaslaver A, Bren A, Ronen M, Itzkovitz S, Kikoin I, Shavit S, Liebermeister W, Surette MG, Alon U (2006). "A comprehensive library of fluorescent transcriptional reporters for Escherichia coli." Nat Methods 3(8);623-8. PMID: 16862137

Other References Related to Gene Regulation

Balaeff04: Balaeff A, Mahadevan L, Schulten K (2004). "Structural basis for cooperative DNA binding by CAP and lac repressor." Structure 12(1);123-32. PMID: 14725772

Cannistraro85: Cannistraro VJ, Kennell D (1985). "The 5' ends of Escherichia coli lac mRNA." J Mol Biol 182(2);241-8. PMID: 2582140

Czarniecki97: Czarniecki D, Noel RJ, Reznikoff WS (1997). "The -45 region of the Escherichia coli lac promoter: CAP-dependent and CAP-independent transcription." J Bacteriol 179(2);423-9. PMID: 8990294

Eschenlauer91: Eschenlauer AC, Reznikoff WS (1991). "Escherichia coli catabolite gene activator protein mutants defective in positive control of lac operon transcription." J Bacteriol 173(16);5024-9. PMID: 1650341

Fischer98: Fischer D, Teich A, Neubauer P, Hengge-Aronis R (1998). "The general stress sigma factor sigmaS of Escherichia coli is induced during diauxic shift from glucose to lactose." J Bacteriol 180(23);6203-6. PMID: 9829928

Flashner88: Flashner Y, Gralla JD (1988). "Dual mechanism of repression at a distance in the lac operon." Proc Natl Acad Sci U S A 1988;85(23);8968-72. PMID: 3143112

Fried96: Fried MG, Hudson JM (1996). "DNA looping and lac repressor-CAP interaction." Science 274(5294);1930-1; author reply 1931-2. PMID: 8984648

Hediger85: Hediger MA, Johnson DF, Nierlich DP, Zabin I (1985). "DNA sequence of the lactose operon: the lacA gene and the transcriptional termination region." Proc Natl Acad Sci U S A 82(19);6414-8. PMID: 3901000

Hoare78: Hoare AM, McLeish A, Thompson H, Alexander-Williams J (1978). "Selection of patients for bile diversion surgery: use of bile acid measurement in fasting gastric aspirates." Gut 19(3);163-5. PMID: 631635

Hudson90: Hudson JM, Fried MG (1990). "Co-operative interactions between the catabolite gene activator protein and the lac repressor at the lactose promoter." J Mol Biol 214(2);381-96. PMID: 2166165

Hudson91: Hudson JM, Fried MG (1991). "The binding of cyclic AMP receptor protein to two lactose promoter sites is not cooperative in vitro." J Bacteriol 173(1);59-66. PMID: 1987134

Jimenez05: Jimenez CR, Li KW, Smit AB, Janse C (2005). "Auto-inhibitory control of peptidergic molluscan neurons and reproductive senescence." Neurobiol Aging NIL. PMID: 15951060

Koli11: Koli P, Sudan S, Fitzgerald D, Adhya S, Kar S (2011). "Conversion of commensal Escherichia coli K-12 to an invasive form via expression of a mutant histone-like protein." MBio 2(5). PMID: 21896677

Lewis05: Lewis M (2005). "The lac repressor." C R Biol 328(6);521-48. PMID: 15950160

Lindemose14: Lindemose S, Nielsen PE, Valentin-Hansen P, Mollegaard NE (2014). "A novel indirect sequence readout component in the E. coli cyclic AMP receptor protein operator." ACS Chem Biol 9(3);752-60. PMID: 24387622

Liu03: Liu M, Gupte G, Roy S, Bandwar RP, Patel SS, Garges S (2003). "Kinetics of transcription initiation at lacP1. Multiple roles of cyclic AMP receptor protein." J Biol Chem 278(41);39755-61. PMID: 12881519

Liu04a: Liu M, Garges S, Adhya S (2004). "lacP1 promoter with an extended -10 motif. Pleiotropic effects of cyclic AMP protein at different steps of transcription initiation." J Biol Chem 279(52);54552-7. PMID: 15385551

Meiklejohn85: Meiklejohn AL, Gralla JD (1985). "Entry of RNA polymerase at the lac promoter." Cell 1985;43(3 Pt 2);769-76. PMID: 3907860

Merkel92: Merkel TJ, Nelson DM, Brauer CL, Kadner RJ (1992). "Promoter elements required for positive control of transcription of the Escherichia coli uhpT gene." J Bacteriol 1992;174(9);2763-70. PMID: 1569008

Miroslavova06: Miroslavova NS, Mitchell JE, Tebbutt J, Busby SJ (2006). "Recruitment of RNA polymerase to Class II CRP-dependent promoters is improved by a second upstream-bound CRP molecule." Biochem Soc Trans 34(Pt 6);1075-8. PMID: 17073754

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Please cite the following article in publications resulting from the use of EcoCyc: Nucleic Acids Research 41:D605-12 2013
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