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tRNA slippage at the tmRNA resume codon
Michael J Trimble1, Amy Minnicus, Kelly P Williams
1Department of Biology, Indiana University, Bloomington, IN 47405, USA.
RNA (New York, N.Y.)
|April 22, 2004
Summary
Bacterial translation resumes on tmRNA at a specific resume codon. A stop codon can induce -2 frameshifting, but only within the tmRNA context, suggesting unique ribosome interactions.
Area of Science:
- Molecular Biology
- Bacterial Genetics
- Ribosome Function
Background:
- Bacterial translation initiation typically occurs on mRNA.
- Transfer-messenger RNA (tmRNA) facilitates rescue of stalled ribosomes.
- Ribosome resumes translation at a specific 'resume codon' on tmRNA.
Purpose of the Study:
- Investigate the mechanism of frameshifting at the tmRNA resume codon.
- Determine the sequence and context requirements for tmRNA-mediated frameshifting.
- Explore the role of specific ribosomal proteins and tRNA interactions.
Main Methods:
- Construction of mutant tmRNAs with altered sequences.
- Analysis of frameshift products using protein expression studies.
- Testing the effect of ribosomal protein L9 deficiency.
Main Results:
- A stop codon (UAA) as the second codon induced high-frequency -2 frameshifting at the resume codon.
- Altering the -2 base abolished frameshift product detection.
- Frameshifting was specific to the tmRNA resume codon context and not observed on regular mRNA or at other tmRNA codons.
Conclusions:
- Frameshifting at the tmRNA resume codon is context-dependent.
- Unusual ribosome states, potentially involving E-site interactions, may destabilize P-site codon-anticodon pairing, promoting slippage.
- Ribosomal protein L9 is not essential for this specific frameshifting event.