Improving Salmonella vector with rec mutation to stabilize the DNA cargoes

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Salmonella species are utilized as vectors for delivering therapeutic molecules for cancer and infectious diseases.
• Maintaining plasmid stability within bacterial vectors is crucial for effective gene delivery.
• The role of specific genes in plasmid recombination within Salmonella enterica remains largely uncharacterized.

Purpose of the Study:

• To investigate the impact of deleting specific genes (recA, recF, recJ) on plasmid DNA recombination in Salmonella enterica.
• To determine if these genetic modifications enhance plasmid stability for potential therapeutic applications.

Main Methods:

• Deletion mutagenesis was performed on recA, recF, and recJ genes in three Salmonella enterica serotypes.
• Intra- and interplasmid recombination frequencies were measured and compared between mutant and wild-type strains.
• Intrachromosomal recombination and plasmid integration frequencies were also assessed.

Main Results:

• RecA and RecF deletions significantly reduced intraplasmid recombination in Salmonella Typhi, and to a lesser extent in Typhimurium and Paratyphi A.
• Both RecA and RecF mutations decreased intraplasmid recombination with intervening sequences across all tested serotypes.
• RecA and RecF deletions lowered interplasmid recombination in Typhimurium and Paratyphi A, but not Typhi.
• RecJ deletions showed a less pronounced effect on plasmid recombination compared to RecA and RecF.
• RecA deletion also reduced intrachromosomal recombination and plasmid integration into the chromosome.

Conclusions:

• RecA and RecF mutations effectively reduce plasmid recombination in Salmonella enterica, though the impact varies by serovar.
• These findings provide valuable insights for engineering stable Salmonella delivery vectors for gene therapy and vaccine development.