The Tricks of Ribosomal Elongation Factors

摘要

Elongation factors (EF) catalyze protein biosynthesis. Two classes of elongation factors can be differentiated: EF-Tu and EF-G in eubacteria and EF-1 and EF-2 in archaebacteria and eukaryotes. They can adopt at least two conformations: one when boundto GDP and another when bound to GTP. In addition, EF-Tu (EF-1) can have still other ligands.The crystal structures of the various forms in which EF-Tu can appear and those of EF-G with and without GDP have afforded exciting insights into the functions of elongation factors as well as into ribosomal mechanisms. The biggest surprise came from thecrystal structure of the ternary complex aminoacyl-tRNA-EF-Tu'GTP. Before we discuss the structures and some of the functional implications we will turn brieflyto the process of protein biosynthesis.