Unlocking genetic potential: harnessing phage for targeted mutagenesis in phage-assisted evolution

Area of Science:

• Molecular Biology
• Biotechnology
• Genetics

Background:

• Off-target mutations pose a challenge in DNA library generation for evolution systems, potentially compromising selective pressure.
• Existing methods struggle to restrict mutations solely to the gene-of-interest (GOI), leading to undesirable genomic alterations.

Purpose of the Study:

• To develop a novel system for targeted mutagenesis within a gene-of-interest (GOI) using phage-assisted evolution.
• To create a diverse mutant library while preventing off-target mutations in the plasmid or host genome.

Main Methods:

• Integration of the MutaT7 system with phage-assisted evolution to create the enhanced mutation phage-assisted evolution (eMPAE) system.
• Phage infection transfers genetic material for targeted gene alteration by the MutaT7 system within host cells.

Main Results:

• The eMPAE system achieved up to 9 mutations in the GOI at a high mutation rate (5.6 mutations kb-1 day-1) without off-target mutations in the 6600 bp plasmid.
• Demonstrated significantly higher targeted mutation efficiency compared to existing methods like eMutaT7 and MP6.
• Validated protein variants from eMPAE exhibit enhanced performance and withstand selective pressure in binding assays.

Conclusions:

• The eMPAE system offers superior targeted mutagenesis, enabling the construction of diverse mutant libraries with minimal risk of off-target mutations.
• This transformative tool is particularly valuable for directed evolution applications, reducing the likelihood of 'cheater' phages.
• The system's modular design allows for easy substitution of GOI and DNA-modifying enzymes.