Casting epPCR (cepPCR): A simple random mutagenesis method to generate high quality mutant libraries.

Area of Science:

• Protein Engineering
• Biotechnology
• Enzyme Engineering

Background:

• Directed evolution is key for engineering industrial enzymes under harsh conditions.
• Error-prone PCR (epPCR) is common but often yields limited beneficial mutations.
• Improving enzyme resistance to organic solvents and ionic liquids remains a challenge.

Purpose of the Study:

• To enhance the identification of beneficial mutations for enzyme engineering.
• To improve the efficiency of directed evolution strategies.
• To increase enzyme resistance to challenging industrial environments.

Main Methods:

• Dividing the Bacillus subtilis lipase (bsla) gene into three fragments.
• Applying error-prone PCR (epPCR) with a high mutation load to each fragment.
• Utilizing a novel 'casting epPCR' (cepPCR) method and combining it with sequence saturation mutagenesis (SeSaM).

Main Results:

• Casting epPCR (cepPCR) doubled the identification of beneficial positions compared to standard epPCR (14% to 29%).
• Combining cepPCR with SeSaM further increased beneficial positions to 39%.
• Analysis of up to 600 mutations per fragment provided insights into optimizing directed evolution campaigns.

Conclusions:

• Casting epPCR is a more effective strategy for generating beneficial mutations in directed evolution.
• The combination of cepPCR and SeSaM offers a powerful approach for enzyme engineering.
• Optimizing screening efforts in directed evolution is crucial for maximizing beneficial outcomes.