Interaction of helix D of elongation factor Tu with helices 4 and 5 of protein L7/12 on the ribosome

JOURNAL OF MOLECULAR BIOLOGY

卷:336

Article

Kothe, U ; Wieden, HJ ; Mohr, D ; Rodnina, MV

关键词: GTP-binding proteins;    rapid kinetics;    fluorescence;    stopped flow;    quench flow;   

DOI  :  10.1016/j.jmb.2003.12.080

来源: Elsevier

【 摘 要 】

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. (C) 2004 Elsevier Ltd. All rights reserved.

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