title: Interaction of helix D of elongation factor Tu with helices 4 and 5 of protein L7/12 on the ribosome.
abstract: Elongation factor Tu (EF-Tu) promotes binding of aminoacyl-tRNA to the A site of the ribosome. Here, we report the effects of mutations in helix D of EF-Tu and in the C-terminal domain of L7/12 on the kinetics of A-site binding. Reaction rates were measured by stopped-flow and quench-flow techniques. The rates of A-site binding were decreased by mutations at positions 144, 145, 148, and 152 in helix D of EF-Tu as well as at positions 65, 66, 69, 70, 73, and 84 in helices 4 and 5 of L7/12. The effect was due primarily to the lower association rate constant of ternary complex binding to the ribosome. These results suggest that helix D of EF-Tu is involved in an initial transient contact with helices 4 and 5 of L7/12 that promotes ternary complex binding to the ribosome. By analogy to the interaction of helix D of EF-Tu with the N-terminal domain of EF-Ts, the contact area is likely to consist of a hydrophobic patch flanked by two salt-bridges.
authors.affiliation: Institute of Physical Biochemistry, University of Witten/Herdecke, 58448 Witten, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Kothe
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Wieden
authors.forename: Dagmar
authors.initials: D
authors.lastname: Mohr
authors.forename: Marina V
authors.initials: MV
authors.lastname: Rodnina
mesh_terms: D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D057927:Hydrophobic and Hydrophilic Interactions; D009154:Mutation; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism; D055672:Static Electricity
chemical_list: D001426:Bacterial Proteins; D012269:Ribosomal Proteins; C016700:ribosomal protein L7-L12; D010444:Peptide Elongation Factor Tu