Ligases;
Forming carbon-oxygen bonds;
Ligases forming aminoacyl-tRNA and related compounds
BRITE hierarchy

L-aspartate:tRNAAsx ligase (AMP-forming)

ATP + L-aspartate + tRNAAsx = AMP + diphosphate + L-aspartyl-tRNAAsx [RN:R03647 R05577]

R03647 R05577
Reaction

ATP [CPD:C00002];
L-aspartate [CPD:C00049];
tRNAAsx

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.

EC 6.1.1.23 created 2002

1  [PMID:10966471]

2  [PMID:9724658]

3  [PMID:9789000]