| EC |
6.1.1.23 |
| Accepted name: |
aspartate—tRNAAsn ligase |
| Reaction: |
ATP + L-aspartate + tRNAAsx = AMP + diphosphate + L-aspartyl-tRNAAsx |
| Other name(s): |
nondiscriminating aspartyl-tRNA synthetase |
| Systematic name: |
L-aspartate:tRNAAsx ligase (AMP-forming) |
| Comments: |
When this enzyme acts on tRNAAsp, it catalyses the same reaction as EC 6.1.1.12, aspartate—tRNA ligase. It has, however, diminished discrimination, so that it can also form aspartyl-tRNAAsn. This relaxation of specificity has been found to result from the absence of a loop in the tRNA that specifically recognizes the third position of the anticodon [1]. This accounts for the ability of this enzyme in, for example, Thermus thermophilus, to recognize both tRNAAsp (GUC anticodon) and tRNAAsn (GUU anticodon). The aspartyl-tRNAAsn is not used in protein synthesis until it is converted by EC 6.3.5.6, asparaginyl-tRNA synthase (glutamine-hydrolysing), into asparaginyl-tRNAAsn. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9027-32-1 |
| References: |
| 1. |
Ibba, M. and Söll, D. Aminoacyl-tRNA synthesis. Annu. Rev. Biochem. 69 (2000) 617–650. [DOI] [PMID: 10966471] |
| 2. |
Schmitt, E., Moulinier, L., Fujiwara, S., Imanaka, T., Thierry, J.C. and Moras, D. Crystal structure of aspartyl-tRNA synthetase from Pyrococcus kodakaraensis KOD: archaeon specificity and catalytic mechanism of adenylate formation. EMBO J. 17 (1998) 5227–5237. [DOI] [PMID: 9724658] |
| 3. |
Becker, H.D. and Kern, D. Thermus thermophilus: a link in evolution of the tRNA-dependent amino acid amidation pathways. Proc. Natl. Acad. Sci. USA 95 (1998) 12832–12837. [DOI] [PMID: 9789000] |
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| [EC 6.1.1.23 created 2002] |
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