Thermodynamic control of -1 programmed ribosomal frameshifting

Area of Science:

• Molecular Biology
• Biophysics
• Computational Biology

Background:

• Ribosome frameshifting is a key translational control mechanism.
• Specific mRNA sequences ('slippery' sequences) and secondary structures can induce ribosomal frameshifting.
• Understanding the biophysical basis of frameshifting is crucial for gene expression regulation.

Purpose of the Study:

• To develop a thermodynamic model using Bayesian statistics to explain -1 programmed ribosome frameshifting.
• To predict frameshifting efficiency based on mRNA-tRNA base pairing in different reading frames.
• To elucidate the roles of tRNA anticodon modifications and ribosome tuning in frameshifting.

Main Methods:

• Measured frameshifting efficiencies for 64 dnaX mRNA variants in vitro.
• Utilized 21 published in vivo frameshifting efficiencies as training data.
• Developed a thermodynamic model based on Bayesian statistics to analyze free-energy differences.

Main Results:

• The model accurately reproduces and predicts frameshifting efficiencies based on tRNA-mRNA base pairing.
• Demonstrated how the free-energy difference between mRNA-tRNA base pairs in the 0 and -1 frames influences frameshifting.
• Showed that tRNA anticodon modifications modulate frameshifting efficiency.

Conclusions:

• The thermodynamic model provides a quantitative framework for understanding programmed ribosome frameshifting.
• Ribosome frameshifting efficiency is predictable from the biophysical interactions between mRNA and tRNA.
• The ribosome actively tunes base-pair interactions to regulate frameshifting outcomes.