title: Structural homology in the amino-terminal domains of two aminoacyl-tRNA synthetases.
abstract: The three-dimensional structures of two animoacyl-tRNA synthetases, the methionyl-tRNA synthetase from Escherichia coli (MetRS) and the tyrosyl-tRNA synthetase from Bacillus stearothermophilus (TyrRS), show a remarkable similarity over a span of about 140 amino acids. The region of homologous folding corresponds to a five-stranded parallel beta-sheet, including a mononucleotide-binding fold. One cysteine and two histidine residues that were found to be invariant in the amino acid sequences occupy similar places in the nucleotide-binding fold. In TyrRS, these residues are close to the adenylate binding site, and in MetRS to the Mg2+-ATP binding site.
mesh_terms: D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases; D004926:Escherichia coli / Q000201:enzymology; D001411:Geobacillus stearothermophilus / Q000201:enzymology; D008718:Methionine-tRNA Ligase; D008958:Models, Molecular; D011487:Protein Conformation; D014448:Tyrosine-tRNA Ligase
chemical_list: D000604:Amino Acyl-tRNA Synthetases; D014448:Tyrosine-tRNA Ligase; D008718:Methionine-tRNA Ligase