Codon usage, transfer RNA availability and mistranslation in amino acid starved bacteria

Area of Science:

• Molecular Biology
• Genetics
• Microbiology

Background:

• Protein synthesis relies on accurate translation of genetic code.
• Amino acid starvation can potentially impact translation fidelity.
• Transfer RNA (tRNA) levels are critical for protein synthesis efficiency.

Purpose of the Study:

• To investigate the fidelity of codon reading in Escherichia coli under amino acid starvation.
• To determine the impact of specific codons on amino acid misincorporation.
• To assess the role of tRNA abundance in amino acid misincorporation.

Main Methods:

• Measuring methionine misincorporation at isoleucine codons (AUU, AUA) in starved cells.
• Assessing histidine misincorporation for glutamine in cells with normal and overproduced histidine-specific tRNA.
• Utilizing Escherichia coli as a model organism.

Main Results:

• Methionine misincorporation at isoleucine residues was found to be very low.
• The frequency of methionine misincorporation was not affected by the specific isoleucine codon (AUU vs. AUA).
• Histidine misincorporation increased significantly in cells overproducing histidine-specific tRNA.

Conclusions:

• Codon identity may have a limited role in preventing specific amino acid misincorporations under starvation.
• Overproduction of specific tRNAs can lead to increased misincorporation events.
• Translation fidelity is sensitive to the cellular concentration of cognate tRNAs.