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Mutational analysis of bacteriophage phi CTX cos site
Virus Research
|December 1, 1996
Summary
The phi CTX bacteriophage, carrying the cytotoxin gene (ctx), converts Pseudomonas aeruginosa into toxin producers. Its DNA replication and expression are linked to specific cos site interactions, crucial for CTX production.
Area of Science:
- Microbiology
- Molecular Biology
- Virology
Background:
- Pseudomonas aeruginosa can be converted into cytotoxin (CTX) producers by the bacteriophage phi CTX.
- The phi CTX genome contains the ctx gene, encoding a pore-forming cytotoxin.
Purpose of the Study:
- To investigate the mechanism of phi CTX DNA replication and CTX gene expression in Pseudomonas aeruginosa.
- To identify the role of the phi CTX cos site and associated proteins in phage DNA processing and toxin production.
Main Methods:
- Isolation and characterization of circular and linear phi CTX DNA forms after infection.
- Transfection of circular phi CTX DNA into Pseudomonas aeruginosa strains.
- In vitro and in vivo assays to analyze protein-DNA interactions at the cos site, including deletion and point mutation analyses.
Main Results:
- phi CTX DNA amplification and ctx gene expression were observed following transfection of circular phi CTX DNA.
- A protein fraction from infected cells demonstrated terminase activity, cleaving the cos site.
- Specific regions of the cos site and flanking sequences were found to be critical for the binding of phage-induced proteins.
Conclusions:
- The study elucidates the role of phi CTX DNA replication and the cos site in mediating CTX production in Pseudomonas aeruginosa.
- Specific protein interactions at the cos site are essential for phi CTX DNA processing and subsequent cytotoxin expression.