Download MendeleyNon-discriminating and discriminating aspartyl-tRNA synthetases differ in the anticodon-binding domain
Charron, C., Roy, H., Blaise, M., Giege, R., Kern, D.(2003) EMBO J 22: 1632-1643
- PubMed: 12660169
- DOI: https://doi.org/10.1093/emboj/cdg148
- Primary Citation of Related Structures:
1N9W - PubMed Abstract:
In most organisms, tRNA aminoacylation is ensured by 20 aminoacyl-tRNA synthetases (aaRSs). In eubacteria, however, synthetases can be duplicated as in Thermus thermophilus, which contains two distinct AspRSs. While AspRS-1 is specific, AspRS-2 is non-discriminating and aspartylates tRNA(Asp) and tRNA(Asn). The structure at 2.3 A resolution of AspRS-2, the first of a non-discriminating synthetase, was solved. It differs from that of AspRS-1 but has resemblance to that of discriminating and archaeal AspRS from Pyrococcus kodakaraensis. The protein presents non-conventional features in its OB-fold anticodon-binding domain, namely the absence of a helix inserted between two beta-strands of this fold and a peculiar L1 loop differing from the large loops known to interact with tRNA(Asp) identity determinant C36 in conventional AspRSs. In AspRS-2, this loop is small and structurally homologous to that in AsnRSs, including conservation of a proline. In discriminating Pyrococcus AspRS, the L1 loop, although small, lacks this proline and is not superimposable with that of AspRS-2 or AsnRS. Its particular status is demonstrated by a loop-exchange experiment that renders the Pyrococcus AspRS non-discriminating.
Organizational Affiliation:
Département Mécanismes et Macromolécules de la Synthèse Protéique et Cristallogenèse, UPR 9002, 15 rue René Descartes, 67084 Strasbourg cedex, France.
