Differentially Optimized Cell-Free Buffer Enables Robust Expression from Unprotected Linear DNA in...

Area of Science:

• Synthetic Biology
• Molecular Biology
• Biochemistry

Background:

• Cell-free systems are crucial for rapid synthetic gene circuit prototyping.
• Linear DNA templates are susceptible to degradation by exonucleases in cell extracts.
• Existing methods to protect linear DNA are time-consuming and resource-intensive.

Purpose of the Study:

• To develop a more efficient method for using linear DNA templates in cell-free systems.
• To eliminate the need for exonuclease inhibitors and DNA-binding proteins.
• To enhance gene expression from linear DNA templates in cell-free systems.

Main Methods:

• Deletion of the recBCD exonuclease gene cluster from the Escherichia coli BL21 genome.
• Optimization of buffer composition, specifically potassium glutamate concentration, for linear DNA templates.
• Characterization of gene expression levels from linear DNA templates in the modified cell-free system.

Main Results:

• The ΔrecBCD E. coli extracts enabled near-plasmid levels of expression from linear DNA templates without additional protection.
• Optimal potassium glutamate concentrations were consistently lower for linear DNA compared to plasmid DNA.
• The exonuclease-deficient extracts demonstrated robustness across multiple batches and experimental conditions in different laboratories.

Conclusions:

• Deleting recBCD provides a simple, efficient, and cost-effective solution for using linear DNA in cell-free systems.
• Tailoring buffer composition is critical for optimizing performance with linear DNA templates.
• This exonuclease deletion strategy is potentially applicable to other species for cell-free synthetic biology.