title: Yeast tRNA(Asp)-aspartyl-tRNA synthetase complex: low resolution crystal structure.
abstract: Yeast aspartyl-tRNA synthetase, a dimer of molecular weight 125,000, and two molecules of its cognate tRNA (Mr = 24160) cocrystallize in the cubic space group I432 (a = 354 A). The crystal structure was solved to low resolution using neutron and X-ray diffraction data. Neutron single crystal diffraction data were collected in five solvents differing by their D2O content in order to use the contrast variation method to distinguish between the protein and tRNA. The synthetase was first located at 40 A resolution using the 65% D2O neutron data (tRNA matched) tRNA molecules were found at 20 A resolution using both neutron and X-ray data. The resulting model was refined against 10 A resolution X-ray data, using density modification and least-squares refinement of the tRNA positions. The crystal structure solved without a priori phase knowledge, was confirmed later by isomorphous replacement. The molecular model of the complex is in good agreement with results obtained in solution by probing the protected part of the tRNA by chemical reagents.
authors.affiliation: Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France.
authors.forename: A
authors.initials: A
authors.lastname: Podjarny
authors.forename: B
authors.initials: B
authors.lastname: Rees
authors.forename: J C
authors.initials: JC
authors.lastname: Thierry
authors.forename: J
authors.initials: J
authors.lastname: Cavarelli
authors.forename: J C
authors.initials: JC
authors.lastname: Jésior
authors.forename: M
authors.initials: M
authors.lastname: Roth
authors.forename: A
authors.initials: A
authors.lastname: Lewitt-Bentley
authors.forename: R
authors.initials: R
authors.lastname: Kahn
authors.forename: B
authors.initials: B
authors.lastname: Lorber
authors.forename: J P
authors.initials: JP
authors.lastname: Ebel
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D001226:Aspartate-tRNA Ligase / Q000378:metabolism*; D003461:Crystallography; D005656:Fungal Proteins / Q000378:metabolism / Q000648:ultrastructure*; D008958:Models, Molecular; D009502:Neutrons; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011487:Protein Conformation; D012331:RNA, Fungal / Q000378:metabolism / Q000648:ultrastructure*; D012345:RNA, Transfer, Amino Acid-Specific / Q000378:metabolism*; D012349:RNA, Transfer, Asp / Q000378:metabolism* / Q000648:ultrastructure; D012441:Saccharomyces cerevisiae / Q000032:analysis; D014961:X-Ray Diffraction
chemical_list: D005656:Fungal Proteins; D012331:RNA, Fungal; D012345:RNA, Transfer, Amino Acid-Specific; D012349:RNA, Transfer, Asp; D000604:Amino Acyl-tRNA Synthetases; D001226:Aspartate-tRNA Ligase