Phosphorylation of elongation factor Tu prevents ternary complex formation

C. Alexander, N. Bilgin, C. Lindschau, J. R. Mesters, B. Kraal, R. Hilgenfeld, V. A. Erdmann, C. Lippmann*

*Corresponding author for this work
66 Citations (Scopus)


The elongation factor Tu (EF-Tu) is a member of the GTP/GDP-binding proteins and interacts with various partners during the elongation cycle of protein biosynthesis thereby mediating the correct binding of amino-acylated transfer RNA (aa-tRNA) to the acceptor site (A-site) of the ribosome. After GTP hydrolysis EF-Tu is released in its GDP-bound state. In vivo, EF-Tu is post-translationally modified by phosphorylation. Here we report that the phosphorylation of EF-Tu by a ribosome associated kinase activity is drastically enhanced by EF-Ts. The antibiotic kirromycin, known to block EF- Tu function, inhibits the modification. This effect is specific, since kirromycin-resistant mutants do become phosphorylated in the presence of the antibiotic. On the other hand, phosphorylated wild-type EF-Tu does not bind kirromycin. Most interestingly, the phosphorylation of EF-Tu abolishes its ability to bind aa-tRNA. In the GTP conformation the site of modification is located at the interface between domains 1 and 3 and is involved in a strong interdomain hydrogen bond. Introduction of a charged phosphate group at this position will change the interaction between the domains, leading to an opening of the molecule reminiscent of the GDP conformation. A model for the function of EF-Tu phosphorylation in protein biosynthesis is presented.

Original languageEnglish
JournalJournal of Biological Chemistry
Issue number24
Pages (from-to)14541-14547
Number of pages7
Publication statusPublished - 1995

Research Areas and Centers

  • Academic Focus: Center for Infection and Inflammation Research (ZIEL)


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