PMID:14985767
| Citation |
Klaholz, BP, Myasnikov, AG and Van Heel, M (2004) Visualization of release factor 3 on the ribosome during termination of protein synthesis. Nature 427:862-5 |
|---|---|
| Abstract |
Termination of protein synthesis by the ribosome requires two release factor (RF) classes. The class II RF3 is a GTPase that removes class I RFs (RF1 or RF2) from the ribosome after release of the nascent polypeptide. RF3 in the GDP state binds to the ribosomal class I RF complex, followed by an exchange of GDP for GTP and release of the class I RF. As GTP hydrolysis triggers release of RF3 (ref. 4), we trapped RF3 on Escherichia coli ribosomes using a nonhydrolysable GTP analogue. Here we show by cryo-electron microscopy that the complex can adopt two different conformational states. In 'state 1', RF3 is pre-bound to the ribosome, whereas in 'state 2' RF3 contacts the ribosome GTPase centre. The transfer RNA molecule translocates from the peptidyl site in state 1 to the exit site in state 2. This translocation is associated with a large conformational rearrangement of the ribosome. Because state 1 seems able to accommodate simultaneously both RF3 and RF2, whose position is known from previous studies, we can infer the release mechanism of class I RFs. |
| Links |
PubMed Online version:10.1038/nature02332 |
| Keywords |
Cryoelectron Microscopy; Escherichia coli/chemistry; Guanosine Triphosphate/metabolism; Models, Molecular; Peptide Chain Termination, Translational; Peptide Termination Factors/chemistry; Peptide Termination Factors/metabolism; Peptide Termination Factors/ultrastructure; Protein Binding; Protein Conformation; RNA, Transfer/genetics; RNA, Transfer/metabolism; Ribosomes/chemistry; Ribosomes/metabolism; Ribosomes/ultrastructure |
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