Structural Requirements For The Ef-Tu-Directed Kinase

The elongation factor Tu is an abundant protein in both prokaryotes and eukaryotes, and plays a central role in protein biosynthesis. It is a multifunctional protein which interacts with RNA, proteins and nucleotides. The function of the protein is the proper alignment of the coding aa-tRNA on the mRNA programmed ribosome. Recently we reported the posttranslational modification by phosphorylation of the prokaryotic elongation factor Tu (EF-Tu) in vivo (1, 2). Position of phosphorylation was determined as threonine 382 (in E. coli), located in a turn of a β-sheet at the c-terminal end of the molecule. Three-dimensional structure analysis revealed, that the site of phosphorylation is localized in the interface between domain 1 and 3 1 the GTP-like conformation (3). The position is absolutely invariant in EF-Tu and even in the eukaryotic counterpart EF-lα (2).