CATH Classification

Domain Context

CATH Clusters

Superfamily Bira Bifunctional Protein; Domain 2
Functional Family Aspartate--tRNA ligase

Enzyme Information

6.1.1.23
Aspartate--tRNA(Asn) ligase.
based on mapping to UniProt Q976I3
ATP + L-aspartate + tRNA(Asx) = AMP + diphosphate + L-aspartyl-tRNA(Asx).
-!- When this enzyme acts on tRNA(Asp), it catalyzes the same reaction as EC 6.1.1.12. -!- It has, however, diminished discrimination, so that it can also form aspartyl-tRNA(Asn). -!- 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. -!- This accounts for the ability of this enzyme in, for example, Thermus thermophilus, to recognize both tRNA(Asp) (GUC anticodon) and tRNA(Asn) (GUU anticodon). -!- The aspartate-tRNA(Asn) is not used in protein synthesis until it is converted by EC 6.3.5.6 into asparaginyl-tRNA(Asn).

UniProtKB Entries (1)

Q976I3
SYDND_SULTO
Sulfurisphaera tokodaii str. 7
Aspartate--tRNA(Asp/Asn) ligase

PDB Structure

PDB 1WYD
External Links
Method X-RAY DIFFRACTION
Organism Escherichia
Primary Citation
Structure of the nondiscriminating aspartyl-tRNA synthetase from the crenarchaeon Sulfolobus tokodaii strain 7 reveals the recognition mechanism for two different tRNA anticodons
Sato, Y., Maeda, Y., Shimizu, S., Hossain, M.T., Ubukata, S., Suzuki, K., Sekiguchi, T., Takenaka, A.
ACTA CRYSTALLOGR.,SECT.D