EC - Asparaginyl-tRNA synthase (glutamine-hydrolysing)

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IntEnz Enzyme Nomenclature


Accepted name:
asparaginyl-tRNA synthase (glutamine-hydrolysing)
Other names:
Asp-tRNAAsn amidotransferase
Asp-tRNAAsn:L-glutamine amido-ligase (ADP-forming)
aspartyl-tRNAAsn amidotransferase
Systematic name:
L-aspartyl-tRNAAsn:L-glutamine amido-ligase (ADP-forming)



This reaction forms part of a two-reaction system for producing asparaginyl-tRNA in Deinococcus radiodurans and other organisms lacking a specific enzyme for asparagine synthesis. In the first step, a non-discriminating ligase (EC, aspartate—tRNAAsn ligase) mischarges tRNAAsn with aspartate, leading to the formation of aspartyl-tRNAAsn. The aspartyl-tRNAAsn is not used in protein synthesis until the present enzyme converts it into asparaginyl-tRNAAsn (aspartyl-tRNAAsp is not a substrate for this enzyme). A glutaminase subunit (cf. EC, glutaminase) produces an ammonia molecule that is transferred by a 30 Å tunnel to a synthase subunit, where it is ligated to the carboxy group that has been activated by phosphorylation. Bacterial GatCAB complexes also has the activity of EC (glutaminyl-tRNA synthase [glutamine-hydrolysing]).

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0050566
CAS Registry Number: 37211-76-0


  1. Min, B., Pelaschier, J.T., Graham, D.E., Tumbula-Hansen, D. and Söll, D.
    Transfer RNA-dependent amino acid biosynthesis: an essential route to asparagine formation.
    Proc. Natl. Acad. Sci. USA 99 : 2678-2683 (2002). [PMID: 11880622]
  2. Curnow, A.W., Tumbula, D.L., Pelaschier, J.T., Min, B. and Söll, D.
    Glutamyl-tRNAGln amidotransferase in Deinococcus radiodurans may be confined to asparagine biosynthesis.
    Proc. Natl. Acad. Sci. USA 95 : 12838-12843 (1998). [PMID: 9789001]
  3. Ibba, M. and Söll, D.
    Aminoacyl-tRNA synthesis.
    Annu. Rev. Biochem. 69 : 617-650 (2000). [PMID: 10966471]

[EC created 2002, modified 2012, modified 2019]