PMID:10917535
| Citation |
Frank, J and Agrawal, RK (2000) A ratchet-like inter-subunit reorganization of the ribosome during translocation. Nature 406:318-22 |
|---|---|
| Abstract |
The ribosome is a macromolecular assembly that is responsible for protein biosynthesis following genetic instructions in all organisms. It is composed of two unequal subunits: the smaller subunit binds messenger RNA and the anticodon end of transfer RNAs, and helps to decode the mRNA; and the larger subunit interacts with the amino-acid-carrying end of tRNAs and catalyses the formation of the peptide bonds. After peptide-bond formation, elongation factor G (EF-G) binds to the ribosome, triggering the translocation of peptidyl-tRNA from its aminoacyl site to the peptidyl site, and movement of mRNA by one codon. Here we analyse three-dimensional cryo-electron microscopy maps of the Escherichia coli 70S ribosome in various functional states, and show that both EF-G binding and subsequent GTP hydrolysis lead to ratchet-like rotations of the small 30S subunit relative to the large 50S subunit. Furthermore, our finding indicates a two-step mechanism of translocation: first, relative rotation of the subunits and opening of the mRNA channel following binding of GTP to EF-G; and second, advance of the mRNA/(tRNA)2 complex in the direction of the rotation of the 30S subunit, following GTP hydrolysis. |
| Links |
PubMed Online version:10.1038/35018597 |
| Keywords |
Biological Transport; Cryoelectron Microscopy; Escherichia coli; Guanosine Triphosphate/metabolism; Hydrolysis; Macromolecular Substances; Models, Molecular; Molecular Conformation; Peptide Elongation Factor G/metabolism; RNA, Messenger/metabolism; RNA, Transfer/metabolism; Ribosomes/chemistry; Ribosomes/metabolism; Ribosomes/ultrastructure |
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