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Ribosomal pausing at a frameshifter RNA pseudoknot is sensitive to reading phase but shows little correlation with
H Kontos1, S Napthine, I Brierley
1Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom.
Molecular and Cellular Biology
|November 20, 2001
Summary
Ribosomal pausing at programmed -1 ribosomal frameshifting sites is influenced by RNA structures, but pausing alone does not guarantee frameshifting. Additional ribosomal events are necessary for efficient frameshifting.
Area of Science:
- Molecular Biology
- Genetics
- Virology
Background:
- Programmed -1 ribosomal frameshifting is a mechanism used by viruses and cells to regulate gene expression.
- Ribosomal pausing at frameshift signals is thought to be a prerequisite for frameshifting, but the precise relationship is unclear.
Purpose of the Study:
- To investigate the role of ribosomal pausing in programmed -1 ribosomal frameshifting.
- To determine the relationship between RNA structure, ribosomal pausing, and frameshifting efficiency.
Main Methods:
- Translational elongation assays
- Ribosome heelprint assays
- Analysis of frameshift signals from infectious bronchitis virus (IBV) and simian retrovirus 1 (SRV1)
Main Results:
- Ribosomal pausing was observed at frameshift signals, positioning the ribosome over the slippery sequence.
- Pausing efficiency did not directly correlate with frameshifting efficiency.
- RNA structures with similar pausing capabilities exhibited different frameshifting efficiencies.
- The reading phase of the ribosome influenced pausing, with the least pausing observed in the phase that promoted the most efficient frameshifting.
Conclusions:
- Ribosomal pausing alone is insufficient to mediate programmed -1 ribosomal frameshifting.
- Additional events or factors are required for efficient frameshifting.
- The phase dependence of pausing suggests an interaction between the ribosome and mRNA secondary structures crucial for unwinding.