Precise Phage Mutagenesis with NgTET-Assisted CRISPR-Cas Systems.

Area of Science:

• Microbiology
• Molecular Biology
• Biotechnology

Background:

• Bacteriophages are crucial for biotechnology and medicine, particularly for combating antibiotic-resistant bacteria.
• Understanding phage gene functions and interactions requires precise genome editing.
• Phage DNA modifications, like cytosine glycosylation, impede conventional genome editing tools such as CRISPR-Cas.

Purpose of the Study:

• To develop an efficient method for site-specific mutagenesis in phage genomes.
• To overcome challenges posed by phage DNA modifications for CRISPR-Cas systems.
• To enable precise genetic engineering of phages for functional studies and therapeutic applications.

Main Methods:

• Utilized the Ten Eleven Translocation (TET) methylcytosine dioxygenase (NgTET) from Naegleria gruberi.
• NgTET temporarily reduces phage DNA modifications by oxidizing hydroxymethylated cytosines.
• This reduction enhances Cas-mediated DNA cleavage for targeted mutagenesis.

Main Results:

• Successfully enabled efficient CRISPR-Cas targeting and precise mutation introduction into phage genomes.
• Demonstrated scarless genome editing, preserving native gene architecture.
• Minimized unintended disruptions to phage regulatory networks.

Conclusions:

• The developed method allows for efficient, scarless, and precise point mutations in phage genomes.
• This approach facilitates detailed functional studies of essential or multifunctional phage proteins.
• Enhances the potential for rational engineering of bacteriophages for therapeutic and biotechnological uses.