PROTEIN-BIOSYNTHESIS - STRUCTURAL STUDIES OF THE ELONGATION CYCLE

The elongation cycle of protein synthesis on ribosomes is catalyzed by the elongation factors EF-Tu and EF-G, A thorough crystallographic an alysis of the structures of the different functional states of EF-Tu h as been made. Furthermore, the structure of EF-G:GDP is the form of EF -G that dissociates from the ribosome, Since it mimics the structure o f the ternary complex of EF-Tu:CTP with aminoacyl-tRNA, which subseque ntly binds to the ribosome, EF-G:GDP leaves an imprint on the ribosome for the ternary complex. In addition, electron cryomicroscopy studies of ribosomes with tRNA as well as the ternary complex bound are begin ning to give a solid structural basis for the functional description o f elongation. (C) 1998 Federation of European Biochemical Societies.