Vibrio cholerae conjugative plasmid pSJ15 contains transposable prophage dVcA1

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Bacteriophages can integrate into bacterial genomes, influencing host properties.
• Transposons and plasmids play key roles in bacterial genetic exchange and evolution.
• Understanding phage integration and transfer mechanisms is crucial for bacterial genetics.

Purpose of the Study:

• To investigate the transposition of defective prophage dVcA1 in Vibrio cholerae.
• To characterize the properties of a novel conjugative plasmid (pSJ15) formed by this integration.
• To elucidate the mechanism of high-frequency chromosomal transfer mediated by the VcA1 prophage.

Main Methods:

• Plasmid conjugation experiments with Vibrio cholerae strains.
• Isolation and characterization of recombinant plasmids.
• Physical mapping and size determination of plasmids.
• Analysis of chromosomal marker transfer during mating.

Main Results:

• Defective prophage dVcA1 transposed to plasmid pSJ5, forming conjugative plasmid pSJ15.
• Plasmid pSJ15 mediated high-frequency, polarized chromosomal transfer in Vibrio cholerae strain 162.
• Transconjugants exhibited phage immunity and cotransferred resistance, indicating stable integration.
• VcA1 prophage integration sites were found to be numerous in both donor and recipient strains.

Conclusions:

• Bacteriophage VcA1, similar to coliphage Mu, exhibits broad site-specific integration capabilities.
• Plasmid pSJ15 functions as an Hfr-like donor, facilitating efficient genetic exchange.
• The VcA1 prophage's ability to integrate at multiple chromosomal locations has significant implications for Vibrio cholerae genetics.