Enhancing the Translational Capacity of E. coli by Resolving the Codon Bias

Area of Science:

• Molecular Biology
• Biotechnology
• Protein Expression

Background:

• Escherichia coli is a common host for heterologous protein production.
• Codon bias between host and source organisms can limit recombinant protein yield.
• Transfer RNA (tRNA) availability is a key factor influencing translation efficiency.

Purpose of the Study:

• To develop a strategy to overcome codon bias in Escherichia coli.
• To enhance the translational capacity of the BL21(DE3) host strain.
• To improve recombinant protein production when rare codons are present.

Main Methods:

• Engineered a novel BL21(DE3)-derived strain, "SixPack", by integrating genes for six low-abundance tRNA species.
• Inserted synthetic tRNA gene fragments into a rRNA operon for dynamic transcriptional control.
• Assessed recombinant protein expression using a panel of proteins with varying codon compositions.

Main Results:

• The SixPack strain demonstrated significantly elevated levels of rare tRNAs during exponential growth.
• Expression assays showed superior performance of SixPack compared to parental BL21(DE3) and a plasmid-based tRNA expression strain.
• The engineered strain effectively resolved codon bias issues, boosting protein production.

Conclusions:

• The SixPack strain offers a robust solution for enhancing heterologous protein expression in Escherichia coli.
• This tRNA-overexpressing strategy effectively addresses codon bias, leading to improved translational efficiency.
• The dynamic control of tRNA levels provides a valuable tool for optimizing recombinant protein production.