Crystal structure of the N-terminal anticodon-binding domain of the nondiscriminating aspartyl-tRNA synthetase from Helicobacter pylori
Songsiriritthigul, C., Suebka, S., Chen, C.-J., Fuengfuloy, P., Chuawong, P.(2017) Acta Crystallogr F Struct Biol Commun 73: 62-69
- PubMed: 28177315 
- DOI: https://doi.org/10.1107/S2053230X16020586
- Primary Citation of Related Structures:  
5GRO - PubMed Abstract: 
The N-terminal anticodon-binding domain of the nondiscriminating aspartyl-tRNA synthetase (ND-AspRS) plays a crucial role in the recognition of both tRNA Asp and tRNA Asn . Here, the first X-ray crystal structure of the N-terminal domain of this enzyme (ND-AspRS 1-104 ) from the human-pathogenic bacterium Helicobacter pylori is reported at 2.0 Å resolution. The apo form of H. pylori ND-AspRS 1-104 shares high structural similarity with the N-terminal anticodon-binding domains of the discriminating aspartyl-tRNA synthetase (D-AspRS) from Escherichia coli and ND-AspRS from Pseudomonas aeruginosa, allowing recognition elements to be proposed for tRNA Asp and tRNA Asn . It is proposed that a long loop (Arg77-Lys90) in this H. pylori domain influences its relaxed tRNA specificity, such that it is classified as nondiscriminating. A structural comparison between D-AspRS from E. coli and ND-AspRS from P. aeruginosa suggests that turns E and F ( 78 GAGL 81 and 83 NPKL 86 ) in H. pylori ND-AspRS play a crucial role in anticodon recognition. Accordingly, the conserved Pro84 in turn F facilitates the recognition of the anticodons of tRNA Asp ( 34 GUC 36 ) and tRNA Asn ( 34 GUU 36 ). The absence of the amide H atom allows both C and U bases to be accommodated in the tRNA-recognition site.
Organizational Affiliation: 
Synchrotron Light Research Institute (Public Organization), 111 University Avenue, Nakhon Ratchasima 30000, Thailand.