HYDROLYSIS OF GTP BY ELONGATION-FACTOR-G DRIVES TRANSFER-RNA MOVEMENTON THE RIBOSOME

Elongation factor G (EF-G) is a GTPase that is involved in the translo cation of bacterial ribosomes along messenger RNA during protein biosy nthesis. In contrast to current models, EF-G-dependent GTP hydrolysis is shown to precede, and greatly accelerate, the rearrangement of the ribosome that leads to translocation. Domain IV of the EF-G structure is crucial for both rapid translocation and subsequent release of the factor from the ribosome. By coupling the free energy of GTP hydrolysi s to translocation, EF-G serves as a motor protein to drive the direct ional movement of transfer and messenger RNAs on the ribosome.