title: Escherichia coli tyrosyl- and methionyl-tRNA synthetases display sequence similarity at the binding site for the 3'-end of tRNA.
abstract: Covalent modification of Escherichia coli tyrosyl-tRNA synthetase (TyrRS) by the 2',3'-dialdehyde derivative of tRNATyr (tRNAox) resulted in a time-dependent inactivation of both ATP-PPi exchange and tRNA aminoacylation activities of the enzyme. In parallel with the inactivation, covalent incorporation of approximately 1 mol of [14C]tRNATyrox/mol of the dimeric synthetase occurred. Intact tRNATyr protected the enzyme against inactivation by the tRNA dialdehyde. Treatment of the TyrRS-[14C]tRNATyr covalent complex with alpha-chymotrypsin produced two labeled peptides (A and B) that were isolated and identified by sequence analysis. Peptides A and B are adjacent and together span residues 227-244 in the primary structure of the enzyme. The three lysine residues in this sequence (lysines-229, -234, and -237) are labeled in a mutually exclusive fashion, with lysine-234 being the most reactive. By analogy with the known three-dimensional structure of the homologous tyrosyl-tRNA synthetase from Bacillus stearothermophilus, these lysines should be part of the C-terminal domain which is presumed to bind the cognate tRNA. Interestingly, the labeled TyrRS structure showed significant similarities to the structure around the lysine residue of E. coli methionyl-tRNA synthetase which is the most reactive toward tRNAMetf(ox) (lysine-335) [Hountondji, C., Blanquet, S., & Lederer, F. (1985) Biochemistry 24, 1175-1180].
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D001665:Binding Sites; D002250:Carbon Radioisotopes; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008718:Methionine-tRNA Ligase / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D012346:RNA, Transfer, Amino Acyl / Q000494:pharmacology*; D014448:Tyrosine-tRNA Ligase / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D002250:Carbon Radioisotopes; D010446:Peptide Fragments; D012346:RNA, Transfer, Amino Acyl; C048449:tRNA, tyrosine-2,3-dialdehyde-; D000604:Amino Acyl-tRNA Synthetases; D014448:Tyrosine-tRNA Ligase; D008718:Methionine-tRNA Ligase