Codon specificity of starvation induced misreading

Area of Science:

• Molecular Biology
• Genetics
• Protein Synthesis

Background:

• Bacteriophage MS2 coat protein synthesis is a model for studying translational fidelity.
• Nutritional stress, such as amino acid starvation, can impact protein synthesis accuracy.
• Mistranslation, the incorporation of incorrect amino acids, can lead to altered protein function.

Purpose of the Study:

• To investigate the impact of asparagine starvation on mistranslation of the bacteriophage MS2 coat protein.
• To quantify the frequency of specific amino acid misincorporations, particularly lysine for asparagine.
• To determine if codon context influences mistranslation rates under starvation conditions.

Main Methods:

• Infection of bacterial cells with bacteriophage MS2.
• Induction of asparagine starvation in infected cells.
• Isolation and purification of mistranslated MS2 coat protein derivatives.
• Peptide analysis and amino acid sequencing to identify specific errors.

Main Results:

• Mistranslated MS2 coat protein was successfully isolated from asparagine-starved cells.
• Lysine for asparagine substitutions were prevalent in the mistranslated proteins.
• A six-fold higher error frequency was observed at AAU codons compared to AAC codons.
• This codon-specific error ratio remained consistent between starved and unstarved cells, despite a 100-fold lower overall error rate in unstarved cells.
• Evidence suggests that codon context influences error frequency for AAC codons.

Conclusions:

• Asparagine starvation significantly increases the overall rate of protein mistranslation in bacteriophage MS2.
• Translational errors exhibit codon-specific biases, with AAU codons being more susceptible to mistranslation than AAC codons.
• Codon context plays a role in modulating the accuracy of amino acid incorporation during translation, even under stress conditions.