title: Aspartyl tRNA-synthetase from Escherichia coli: flexibility and adaptability to the substrates.
abstract: The crystal structure of aspartyl-tRNA synthetase from Escherichia coli has been determined to a resolution of 2.7 A. The structure is compared to the same enzyme co-crystallized with tRNA(Asp) and containing aspartyl adenylate or ATP. The asymmetric unit contains three monomers of the enzyme. While most parts of the protein show no significant differences in the three monomers, a few regions cannot be superimposed. Those regions are characterized by a high B-factor, and consist mostly of loops that make contacts with the tRNA in the complexes. The flexibility of the protein is seen at a global level, by the observation of a 10 to 15 degrees rotation of the N-terminal and insertion domains upon tRNA binding, and at the level of the individual amino acid residues, by main-chain and side-chain rearrangements. In contrast to these induced-fit conformational changes, a few residues essential for the tRNA anticodon or aspartyl-adenylate recognition exist in a predefined conformation, ensured by specific interactions within the protein.
authors.affiliation: UPR 9004, Laboratoire de Biologie et de Génomique Structurales, Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 rue Laurent Fries, Illkirch, 67400, France.
authors.forename: B
authors.initials: B
authors.lastname: Rees
authors.forename: G
authors.initials: G
authors.lastname: Webster
authors.forename: M
authors.initials: M
authors.lastname: Delarue
authors.forename: M
authors.initials: M
authors.lastname: Boeglin
authors.forename: D
authors.initials: D
authors.lastname: Moras
mesh_terms: D000249:Adenosine Monophosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000926:Anticodon / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001226:Aspartate-tRNA Ligase / Q000737:chemistry* / Q000378:metabolism*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D020029:Base Pairing / Q000235:genetics; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018583:Pliability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012346:RNA, Transfer, Amino Acyl / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012399:Rotation
chemical_list: D000926:Anticodon; D012346:RNA, Transfer, Amino Acyl; C052755:aspartyl adenylate; D001224:Aspartic Acid; D000249:Adenosine Monophosphate; D000255:Adenosine Triphosphate; D001226:Aspartate-tRNA Ligase