|Gene:||guaA||Accession Numbers: EG10420 (MetaCyc), b2507, ECK2503|
Species: Escherichia coli K-12 substr. MG1655
Subunit composition of
GMP synthetase = [GuaA]2
GMP synthetase = GuaA
GMP synthetase catalyzes the glutamine- or ammonia-dependent synthesis of GMP from XMP [Patel75].
GMP synthetase contains an N-terminal glutamine amide transfer (GAT) domain [Zalkin85a], a central ATP-pyrophosphatase (ATPP) domain, and a C-terminal dimerization domain [Tesmer96]. The GAT domain utilizes glutamine to generate ammonia, which is then transferred to the ATPP domain containing the adenylylated XMP intermediate via a substrate-protective channel or tunnel.
A protein consisting only of the ATPP and dimerization domains of GMP synthetase dimerizes in solution and has similar Km values for ATP, XMP, and ammonia as the full-length protein. However, the rate of catalysis using ammonia as a substrate is dramatically increased, possibly due to enhanced access to the active site [Abbott06]. Rapid kinetics studies of the full-length enzyme allowed analysis of the catalytic cycle, including observation of the enzyme-bound adenylylated XMP intermediate and the functional role of a substrate-induced conformational change [Oliver13]. A model of a catalytically active structure of the enzyme showed the presence of an ammonia tunnel and an interdomain salt bridge at its edge, between H186 in the glutaminase domain and E383 in the synthetase domain. Mutagenesis of these residues resulted in significantly reduced glutaminase activity and uncoupling of the two half reactions [Oliver14].
A crystal stucture of GMP synthetase has been solved at 2.2 Å resolution [Tesmer94, Tesmer96]. The enzyme from E. coli B is a dimer in solution [Sakamoto72], while the crystal structure of GMP synthetase contained a dimer of dimers.
Strains containing a guaA null mutation are auxotrophic for guanine [Lambden73, Joyce06]. A guaA null mutant contains modestly higher levels of xanthine in RNA, potentially interfering with RNA function [Pang12].
A guaA-disrupted mutant was used to shut down the XMP to GMP reaction in an inosine-producing strain of E. coli [Shimaoka06].
|Map Position: [2,628,980 <- 2,630,557]|
Molecular Weight of Polypeptide: 58.679 kD (from nucleotide sequence)
Molecular Weight of Multimer: 126 kD (experimental) [Sakamoto72]
Unification Links: ASAP:ABE-0008254 , CGSC:657 , DIP:DIP-9852N , EchoBASE:EB0415 , EcoGene:EG10420 , EcoliWiki:b2507 , ModBase:P04079 , OU-Microarray:b2507 , PortEco:guaA , Pride:P04079 , Protein Model Portal:P04079 , RefSeq:NP_417002 , RegulonDB:EG10420 , SMR:P04079 , String:511145.b2507 , UniProt:P04079
Relationship Links: InterPro:IN-FAMILY:IPR001674 , InterPro:IN-FAMILY:IPR004739 , InterPro:IN-FAMILY:IPR014729 , InterPro:IN-FAMILY:IPR017926 , InterPro:IN-FAMILY:IPR022310 , InterPro:IN-FAMILY:IPR022955 , InterPro:IN-FAMILY:IPR025777 , InterPro:IN-FAMILY:IPR029062 , PDB:Structure:1GPM , Pfam:IN-FAMILY:PF00117 , Pfam:IN-FAMILY:PF00958 , Pfam:IN-FAMILY:PF02540 , Prosite:IN-FAMILY:PS51273 , Prosite:IN-FAMILY:PS51553
|Biological Process:||GO:0006177 - GMP biosynthetic process
[UniProtGOA12, UniProtGOA11a, GOA06, GOA01a, Lambden73]
GO:0006164 - purine nucleotide biosynthetic process [UniProtGOA11a, GOA01a]
GO:0006541 - glutamine metabolic process [UniProtGOA11a, GOA06]
|Molecular Function:||GO:0003921 - GMP synthase activity
GO:0003922 - GMP synthase (glutamine-hydrolyzing) activity [GOA06, GOA01, GOA01a, Deras99]
GO:0042802 - identical protein binding [Lasserre06]
GO:0042803 - protein homodimerization activity [Sakamoto72]
GO:0000166 - nucleotide binding [UniProtGOA11a]
GO:0005524 - ATP binding [UniProtGOA11a, GOA06, GOA01a]
GO:0016462 - pyrophosphatase activity [GOA01a]
GO:0016874 - ligase activity [UniProtGOA11a]
|Cellular Component:||GO:0005829 - cytosol [DiazMejia09, Ishihama08, Lasserre06]|
|MultiFun Terms:||metabolism → biosynthesis of building blocks → nucleotides → purine biosynthesis|
|metabolism → central intermediary metabolism → nucleotide and nucleoside conversions|
Enzymatic reaction of: xanthosine-5'-phosphate:L-glutamine amido-ligase (AMP-forming) (GMP synthetase)
Synonyms: GMP synthetase (glutamine-hydrolysing), glutamine amidotransferase, GMP synthetase, XMP aminase, GMPS
EC Number: 184.108.40.206
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.
The reaction is physiologically favored in the direction shown.
In Pathways: L-glutamine degradation I , superpathway of histidine, purine, and pyrimidine biosynthesis , superpathway of purine nucleotides de novo biosynthesis II , superpathway of guanosine nucleotides de novo biosynthesis II , superpathway of guanosine nucleotides de novo biosynthesis I , guanosine ribonucleotides de novo biosynthesis
Early assays of the enzymatic activity (e.g. [Spector74, Patel77, Patel75, Zalkin77, Spector75, Sakamoto72, vonderSaal85a]) were performed with enzyme purified from E. coli B 96, a purine-requiring derivative of E. coli B.
pH(opt): 8.3 [Patel75]
Enzymatic reaction of: xanthosine-5'-phosphate:ammonia ligase (AMP-forming) (GMP synthetase)
Synonyms: xanthosine-5'-phosphate ammonia ligase, GMP synthetase, XMP aminase, GMP synthetase (ammonia dependent), xanthosine 5'-phosphate aminase
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.
Early assays of the enzymatic activity (e.g. [Spector74, Patel77, Patel75, Zalkin77, Spector75, Sakamoto72, vonderSaal85a]) were performed with enzyme purified from E. coli B 96, a purine-requiring derivative of E. coli B. A variety of inhibitors of the enzyme were tested in [Spector75].
|Feature Class||Location||Attached Group||Citations||Comment|
|Conserved-Region||9 -> 207|
|Conserved-Region||208 -> 400|
|Nucleotide-Phosphate-Binding-Region||235 -> 241||ATP|
10/20/97 Gene b2507 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10420; confirmed by SwissProt match.
Abbott06: Abbott JL, Newell JM, Lightcap CM, Olanich ME, Loughlin DT, Weller MA, Lam G, Pollack S, Patton WA (2006). "The Effects of Removing the GAT Domain from E. coli GMP Synthetase." Protein J 25;483-491. PMID: 17103135
Deras99: Deras ML, Chittur SV, Davisson VJ (1999). "N2-hydroxyguanosine 5'-monophosphate is a time-dependent inhibitor of Escherichia coli guanosine monophosphate synthetase." Biochemistry 38(1);303-10. PMID: 9890911
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
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
Lasserre06: Lasserre JP, Beyne E, Pyndiah S, Lapaillerie D, Claverol S, Bonneu M (2006). "A complexomic study of Escherichia coli using two-dimensional blue native/SDS polyacrylamide gel electrophoresis." Electrophoresis 27(16);3306-21. PMID: 16858726
Oliver13: Oliver JC, Linger RS, Chittur SV, Davisson VJ (2013). "Substrate activation and conformational dynamics of guanosine 5'-monophosphate synthetase." Biochemistry 52(31);5225-35. PMID: 23841499
Oliver14: Oliver JC, Gudihal R, Burgner JW, Pedley AM, Zwierko AT, Davisson VJ, Linger RS (2014). "Conformational changes involving ammonia tunnel formation and allosteric control in GMP synthetase." Arch Biochem Biophys 545;22-32. PMID: 24434004
Pang12: Pang B, McFaline JL, Burgis NE, Dong M, Taghizadeh K, Sullivan MR, Elmquist CE, Cunningham RP, Dedon PC (2012). "Defects in purine nucleotide metabolism lead to substantial incorporation of xanthine and hypoxanthine into DNA and RNA." Proc Natl Acad Sci U S A 109(7);2319-24. PMID: 22308425
Shimaoka06: Shimaoka M, Takenaka Y, Mihara Y, Kurahashi O, Kawasaki H, Matsui H (2006). "Effects of xapA and guaA disruption on inosine accumulation in Escherichia coli." Biosci Biotechnol Biochem 70(12);3069-72. PMID: 17151449
Tesmer94: Tesmer JJ, Stemmler TL, Penner-Hahn JE, Davisson VJ, Smith JL (1994). "Preliminary X-ray analysis of Escherichia coli GMP synthetase: determination of anomalous scattering factors for a cysteinyl mercury derivative." Proteins 18(4);394-403. PMID: 8208731
Tesmer96: Tesmer JJ, Klem TJ, Deras ML, Davisson VJ, Smith JL (1996). "The crystal structure of GMP synthetase reveals a novel catalytic triad and is a structural paradigm for two enzyme families." Nat Struct Biol 3(1);74-86. PMID: 8548458
vonderSaal85a: von der Saal W, Crysler CS, Villafranca JJ (1985). "Positional isotope exchange and kinetic experiments with Escherichia coli guanosine-5'-monophosphate synthetase." Biochemistry 24(20);5343-50. PMID: 3907701
Zalkin85a: Zalkin H, Argos P, Narayana SV, Tiedeman AA, Smith JM (1985). "Identification of a trpG-related glutamine amide transfer domain in Escherichia coli GMP synthetase." J Biol Chem 260(6);3350-4. PMID: 2982857
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