TG1 integrase-based system for site-specific gene integration into bacterial genomes

Area of Science:

• Molecular Biology
• Genetics
• Microbiology

Background:

• Serine-type phage integrases mediate site-specific recombination between phage (attP) and bacterial (attB) attachment sites.
• Previous work established an in vivo system using actinophage TG1 integrase for integrating ~2-kbp DNA into Escherichia coli.
• These integrases and their target sites are functional in heterologous cellular environments.

Purpose of the Study:

• To analyze TG1 integrase-mediated integration of larger DNA fragments (~10 kbp) into various genomic locations in E. coli.
• To develop an efficient system for large DNA integration using TG1 integrase.
• To investigate factors influencing the efficiency of serine-type integrase-mediated genomic integration.

Main Methods:

• Utilized actinophage TG1 integrase for site-specific recombination.
• Introduced ~10-kbp DNA fragments containing att sites into E. coli genomes with pre-inserted att sites.
• Compared integration efficiencies at different genomic locations and with different att site orientations.

Main Results:

• Developed a system achieving ~10^4 transformants/μg DNA for integrating ~10-kbp DNA.
• Integration of attB-containing DNA into attP-containing genomes was more efficient than the reverse.
• Targeting attP sites near oriC and migS significantly enhanced integration efficiency compared to other regions.

Conclusions:

• Genomic accessibility of the target att site (attP) is crucial for efficient serine-type integrase-mediated integration in heterologous cells.
• The oriC-migS region, located at cell poles during segregation, may offer increased accessibility.
• Findings support the development of serine-type integrase systems for genomic engineering in diverse bacterial species.