anticodon and 4-fluorotryptophan

The 19F nuclear magnetic resonance (NMR) spectra of 4-fluorotryptophan (4-F-Trp)-labeled Escherichia coli arginyl-tRNA synthetase (ArgRS) show that there are distinct conformational changes in the catalytic core and tRNA anticodon stem and loop-binding domain of the enzyme, when arginine and tRNA(Arg) are added to the unliganded enzyme. We have assigned five fluorine resonances of 4-F-Trp residues (162, 172, 228, 349 and 446) in the spectrum of the fluorinated enzyme by site-directed mutagenesis. The local conformational changes of E. coli ArgRS induced by its substrates observed herein by 19F NMR are similar to those of crystalline yeast homologous enzyme.

Topics: Anticodon; Arginine; Arginine-tRNA Ligase; Binding Sites; Catalytic Domain; Escherichia coli; Magnetic Resonance Spectroscopy; Models, Molecular; Protein Conformation; Protein Structure, Secondary; RNA, Transfer, Arg; Substrate Specificity; Tryptophan