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Pathway Description
Galactose utilization: galE, galT, galK, galM
Escherichia coli K-12
Category:
Metabolite Pathway
Sub-Category:
Signaling
Created: 2025-03-25
Last Updated: 2025-07-22
The regulation of the galETKM operon. The operon is inhibited by galR (HTH-type transcriptional regulator) and activated by galactose. The presence of galactose causes galR to release the promoter, allowing transcription of the operon. The operon has four products: galE (UDP-glucose 4-epimerase), galT (Galactose-1-phosphate uridylyltransferase), galK (Galactokinase) and galM (Aldose 1-epimerase). All of these products are enzymes used in the utilization of galactose (galactose to UDP-galactose). GalK is used to turn galactose to galactose-1-phosphate. GalT is used to turn UDP-glucose to UDP-galactose, while galE catalyzes the reverse reaction. GalM is used to change alpha-D-glucose to beta-D-glucose.
References
Galactose utilization: galE, galT, galK, galM References
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Pubmed: 35883524
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Pubmed: 38058119
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Pubmed: 4555404
Wang X, Ji SC, Yun SH, Jeon HJ, Kim SW, Lim HM: Expression of each cistron in the gal operon can be regulated by transcription termination and generation of a galk-specific mRNA, mK2. J Bacteriol. 2014 Jul;196(14):2598-606. doi: 10.1128/JB.01577-14. Epub 2014 May 2.
Pubmed: 24794565
Lemaire HG, Muller-Hill B: Nucleotide sequences of the gal E gene and the gal T gene of E. coli. Nucleic Acids Res. 1986 Oct 10;14(19):7705-11. doi: 10.1093/nar/14.19.7705.
Pubmed: 3022232
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Pubmed: 8905232
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Pubmed: 9278503
Wong LJ, Sheu KF, Lee SL, Frey PA: Galactose-1-phosphate uridylyltransferase: isolation and properties of a uridylyl-enzyme intermediate. Biochemistry. 1977 Mar 8;16(5):1010-6. doi: 10.1021/bi00624a032.
Pubmed: 321007
Debouck C, Riccio A, Schumperli D, McKenney K, Jeffers J, Hughes C, Rosenberg M, Heusterspreute M, Brunel F, Davison J: Structure of the galactokinase gene of Escherichia coli, the last (?) gene of the gal operon. Nucleic Acids Res. 1985 Mar 25;13(6):1841-53. doi: 10.1093/nar/13.6.1841.
Pubmed: 3158881
Bouffard GG, Rudd KE, Adhya SL: Dependence of lactose metabolism upon mutarotase encoded in the gal operon in Escherichia coli. J Mol Biol. 1994 Dec 2;244(3):269-78. doi: 10.1006/jmbi.1994.1728.
Pubmed: 7966338
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Pubmed: 16738553
Daley DO, Rapp M, Granseth E, Melen K, Drew D, von Heijne G: Global topology analysis of the Escherichia coli inner membrane proteome. Science. 2005 May 27;308(5726):1321-3. doi: 10.1126/science.1109730.
Pubmed: 15919996
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