PMID:14672708
| Citation |
Yao, YN, Zhang, QS, Yan, XZ, Zhu, G and Wang, ED (2004) Escherichia coli tRNA(4)(Arg)(UCU) induces a constrained conformation of the crucial Omega-loop of arginyl-tRNA synthetase. Biochem. Biophys. Res. Commun. 313:129-34 |
|---|---|
| Abstract |
Previous investigations show that tRNA(Arg)-induced conformational changes of arginyl-tRNA synthetase (ArgRS) Omega-loop region (Escherichia coli (E. coli), Ala451-Ala457) may contribute to the productive conformation of the enzyme catalytic core, and E. coli tRNA(2)(Arg)(ICG)-bound and -free conformations of the Omega-loop exchange at an intermediate rate on NMR timescale. Herein, we report that E. coli ArgRS catalyzes tRNA(2)(Arg)(ICG) and tRNA(4)(Arg)(UCU) with similar efficiencies. However, 19F NMR spectroscopy of 4-fluorotryptophan-labeled E. coli ArgRS reveals that the tRNA(4)(Arg)(UCU)-bound and -free conformations of the Omega-loop region interconvert very slowly and the lifetime of bound conformation is much longer than 0.33 ms. Therefore, tRNA(4)(Arg)(UCU) differs from tRNA(2)(Arg)(ICG) in the conformation-exchanging rate of the Omega-loop. Comparative structure model of E. coli ArgRS is presented to rationalize these 19F NMR data. Our 19F NMR and catalytic assay results suggest that the tRNA(Arg)-induced conformational changes of Omega-loop little contribute to the productive conformation of ArgRS catalytic core. |
| Links | |
| Keywords |
Arginine/metabolism; Arginine-tRNA Ligase/chemistry; Arginine-tRNA Ligase/metabolism; Catalytic Domain; Escherichia coli/enzymology; Kinetics; Models, Molecular; Nuclear Magnetic Resonance, Biomolecular/methods; Protein Conformation; RNA, Transfer, Arg/genetics; RNA, Transfer, Arg/metabolism; Tryptophan/analogs & derivatives; Tryptophan/metabolism |
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