Reaction: ATP + XMP + L-glutamine + H2O = AMP + diphosphate + GMP + L-glutamate (overall reaction)
(1a) L-glutamine + H2O = L-glutamate + NH3
(1b) ATP + XMP + NH3 = AMP + diphosphate + GMP
For diagram of reaction click here.
Glossary: XMP = xanthosine 5'-phosphate
Other name(s): GMP synthetase (glutamine-hydrolysing); guanylate synthetase (glutamine-hydrolyzing); guanosine monophosphate synthetase (glutamine-hydrolyzing); xanthosine 5'-phosphate amidotransferase; guanosine 5'-monophosphate synthetase
Systematic name: xanthosine-5'-phosphate:L-glutamine amido-ligase (AMP-forming)
Comments: Involved in the de novo biosynthesis of guanosine nucleotides. An N-terminal glutaminase domain binds L-glutamine and generates ammonia, which is transferred by a substrate-protective tunnel to the ATP-pyrophosphatase domain. The enzyme can catalyse the second reaction alone in the presence of ammonia.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37318-71-1
1. Lagerkvist, U. Biosynthesis of guanosine 5'-phosphate. II. Amination of xanthosine 5'-phosphate by purified enzyme from pigeon liver. J. Biol. Chem. 233 (1958) 143-149. [PMID: 13563458]
2. Abrams, R. and Bentley, M. Biosynthesis of nucleic acid purines. III. Guanosine 5'-phosphate formation from xanthosine 5'-phosphate and L-glutamine. Arch. Biochem. Biophys. 79 (1959) 91-110.
3. Zalkin, H., Argos, P., Narayana, S.V., Tiedeman, A.A. and Smith, J.M. Identification of a trpG-related glutamine amide transfer domain in Escherichia coli GMP synthetase. J. Biol. Chem. 260 (1985) 3350-3354. [PMID: 2982857]
4. Abbott, J.L., Newell, J.M., Lightcap, C.M., Olanich, M.E., Loughlin, D.T., Weller, M.A., Lam, G., Pollack, S. and Patton, W.A. The effects of removing the GAT domain from E. coli GMP synthetase. Protein J. 25 (2006) 483-491. [PMID: 17103135]