1b8a
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ASPARTYL-TRNA SYNTHETASE
OverviewOverview
The crystal structure of aspartyl-tRNA synthetase (AspRS) from Pyrococcus, kodakaraensis was solved at 1.9 A resolution. The sequence and, three-dimensional structure of the catalytic domain are highly homologous, to those of eukaryotic AspRSs. In contrast, the N-terminal domain, whose, function is to bind the tRNA anticodon, is more similar to that of, eubacterial enzymes. Its structure explains the unique property of, archaeal AspRSs of accommodating both tRNAAsp and tRNAAsn. Soaking the, apo-enzyme crystals with ATP and aspartic acid both separately and, together allows the adenylate formation to be followed. Due to the, asymmetry of the dimeric enzyme in the crystalline state, different steps, of the reaction could be visualized within the same crystal. Four, different states of the aspartic acid activation reaction could thus be, characterized, revealing the functional correlation of the observed, conformational changes. The binding of the amino acid substrate induces, movement of two invariant loops which secure the position of the peptidyl, moiety for adenylate formation. An unambiguous spatial and functional, assignment of three magnesium ion cofactors can be made. This study shows, the important role of residues present in both archaeal and eukaryotic, AspRSs, but absent from the eubacterial enzymes.
About this StructureAbout this Structure
1B8A is a Single protein structure of sequence from Thermococcus kodakarensis with MN and ATP as ligands. Active as Aspartate--tRNA ligase, with EC number 6.1.1.12 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of aspartyl-tRNA synthetase from Pyrococcus kodakaraensis KOD: archaeon specificity and catalytic mechanism of adenylate formation., Schmitt E, Moulinier L, Fujiwara S, Imanaka T, Thierry JC, Moras D, EMBO J. 1998 Sep 1;17(17):5227-37. PMID:9724658
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