title: Visualization of elongation factor Tu on the Escherichia coli ribosome.
abstract: The delivery of a specific amino acid to the translating ribosome is fundamental to protein synthesis. The binding of aminoacyl-transfer RNA to the ribosome is catalysed by the elongation factor Tu (EF-Tu). The elongation factor, the aminoacyl-tRNA and GTP form a stable 'ternary' complex that binds to the ribosome. We have used electron cryomicroscopy and angular reconstitution to visualize directly the kirromycin-stalled ternary complex in the A site of the 70S ribosome of Escherichia coli. Electron cryomicroscopy had previously given detailed ribosomal structures at 25 and 23 A resolution, and was used to determine the position of tRNAs on the ribosome. In particular, the structures of pre-translocational (tRNAs in A and P sites) and post-translocational ribosomes (P and E sites occupied) were both visualized at a resolution of approximately 20 A. Our three-dimensional reconstruction at 18 A resolution shows the ternary complex spanning the inter-subunit space with the acceptor domain of the tRNA reaching into the decoding centre. Domain 1 (the G domain) of the EF-Tu is bound both to the L7/L12 stalk and to the 50S body underneath the stalk, whereas domain 2 is oriented towards the S12 region on the 30S subunit.
authors.affiliation: Imperial College of Science, Medicine and Technology, Department of Biochemistry, London, UK.
authors.forename: H
authors.initials: H
authors.lastname: Stark
authors.forename: M V
authors.initials: MV
authors.lastname: Rodnina
authors.forename: J
authors.initials: J
authors.lastname: Rinke-Appel
authors.forename: R
authors.initials: R
authors.lastname: Brimacombe
authors.forename: W
authors.initials: W
authors.lastname: Wintermeyer
authors.forename: M
authors.initials: M
authors.lastname: van Heel
mesh_terms: D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D011487:Protein Conformation; D011728:Pyridones / Q000494:pharmacology; D012343:RNA, Transfer / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D011728:Pyridones; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D010444:Peptide Elongation Factor Tu; C008536:mocimycin