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Post-termination complex disassembly by ribosome recycling factor, a functional tRNA mimic
Go Hirokawa1, Michael C Kiel, Aiko Muto
1Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
The EMBO Journal
|May 1, 2002
Summary
Ribosome recycling factor (RRF) and elongation factor G (EF-G) disassemble ribosome complexes. Inhibitors reveal that tRNA release precedes mRNA release, with RRF and EF-G coordinating this process.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Ribosome structure and function are crucial for protein synthesis.
- Ribosome recycling is essential for maintaining cellular protein synthesis efficiency.
- The roles of ribosome recycling factor (RRF) and elongation factor G (EF-G) in ribosome disassembly are not fully elucidated.
Purpose of the Study:
- To investigate the mechanism of post-termination ribosomal complex disassembly.
- To determine the sequential order of mRNA and tRNA release.
- To elucidate the roles of RRF and EF-G in ribosome recycling.
Main Methods:
- In vitro assays using purified components.
- Treatment with translocation inhibitors (thiostrepton, viomycin, aminoglycosides, fusidic acid).
- Use of a GTP analog to stabilize EF-G binding.
Main Results:
- Translocation inhibitors blocked both mRNA and tRNA release.
- Fusidic acid and a GTP analog inhibited mRNA but not tRNA release.
- tRNA release is a prerequisite for mRNA release and can occur partially with EF-G alone.
- RRF and EF-G are released from the ribosome during mRNA release.
- RRF-mediated dissociation of 70S ribosomes into subunits by IF3.
Conclusions:
- The data support a model where RRF and EF-G sequentially disassemble the post-termination complex.
- tRNA release precedes mRNA release, mediated by RRF translocation and EF-G action.
- RRF and EF-G dissociation from the ribosome are the final steps in mRNA release.