The Enzyme Database

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Accepted name: asparaginyl-tRNA synthase (glutamine-hydrolysing)
Reaction: ATP + L-aspartyl-tRNAAsn + L-glutamine + H2O = ADP + phosphate + L-asparaginyl-tRNAAsn + L-glutamate
(1a) L-glutamine + H2O = L-glutamate + NH3
(1b) ATP + L-aspartyl-tRNAAsn = ADP + 4-phosphooxy-L-aspartyl-tRNAAsn
(1c) 4-phosphooxy-L-aspartyl-tRNAAsn + NH3 = L-asparaginyl-tRNAAsn + phosphate
Other name(s): Asp-AdT; Asp-tRNAAsn amidotransferase; aspartyl-tRNAAsn amidotransferase; Asn-tRNAAsn:L-glutamine amido-ligase (ADP-forming); aspartyl-tRNAAsn:L-glutamine amido-ligase (ADP-forming); GatCAB
Systematic name: L-aspartyl-tRNAAsn:L-glutamine amido-ligase (ADP-forming)
Comments: 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: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 37211-76-0
1.  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 (1998) 12838–12843. [DOI] [PMID: 9789001]
2.  Ibba, M. and Söll, D. Aminoacyl-tRNA synthesis. Annu. Rev. Biochem. 69 (2000) 617–650. [DOI] [PMID: 10966471]
3.  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 (2002) 2678–2683. [DOI] [PMID: 11880622]
[EC created 2002, modified 2012, modified 2019]

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