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Plasmid R46 provides a function that promotes recA-independent deletion, fusion and resolution of replicon
Abstract:
We report that plasmid R46 provides a function which promotes recA-independent deletion, replicon fusion, and resolution of the fusion. R46 belongs to the incompatibility group N and specifies resistance to ampicillin, tetracycline, streptomycin and sulfonamide. Four kinds of deletion derivatives were observed by selection for susceptability to tetracycline from ampicillin-resistant clones. A common region, will be called alpha region thereafter, was postulated to be involved in these deletions. The replicon fusion occurred by a conjugative mobilization of each derivative with plasmid R388. The fusion was suggested to contain both replicons linked at each junction by the sequence in the alpha region in direct orientation. The resolution of the replicon fusion was found between two alpha regions and a consequently generated, parental deletion derivative and an R388 derivative which gained one alpha region. It is possible that the alpha region contains one potential Insertion Sequence (IS) element. These events were also speculated to occur as a consequence of insertion of the potential IS onto the intramolecular or intermolecular target sequence, or reciprocal recombination between two potential IS elements.
Insights
Plasmid R46 facilitates recA-independent DNA deletion and replicon fusion. This process involves a specific "alpha region" potentially containing an Insertion Sequence (IS) element, driving genetic rearrangements.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- Plasmid R46, belonging to incompatibility group N, confers resistance to multiple antibiotics.
- Previous studies have not fully elucidated the mechanisms behind plasmid-mediated genetic rearrangements.
Purpose of the Study:
- To investigate the recA-independent functions of plasmid R46.
- To characterize the molecular basis of deletion, replicon fusion, and resolution mediated by R46.
Main Methods:
- Selection of ampicillin-resistant clones and subsequent screening for tetracycline susceptibility to identify deletion derivatives.
- Conjugative mobilization of R46 deletion derivatives with plasmid R388 to induce and study replicon fusion.
- Analysis of the genetic structures resulting from fusion and resolution events.
Main Results:
- Plasmid R46 mediates recA-independent deletion, replicon fusion, and resolution.
- A common DNA region, termed the 'alpha region', is implicated in these genetic events.
- The alpha region likely contains a potential Insertion Sequence (IS) element, explaining observed deletions and fusions through insertion or recombination.
Conclusions:
- The 'alpha region' of plasmid R46 plays a crucial role in mediating DNA rearrangements.
- These rearrangements, including deletion and replicon fusion/resolution, are likely driven by the activity of a potential IS element within the alpha region.
- The findings provide insights into plasmid-mediated genetic plasticity and horizontal gene transfer mechanisms.