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Construction and some properties of packageable plasmid F
Molecular & General Genetics : MGG
|January 16, 1979
Summary
Researchers created a novel hybrid plasmid, packageable in lambda phage, by combining F plasmid, Staphylococcus plasmid, and lambda phage DNA. This engineered DNA molecule replicates autonomously and can be efficiently delivered into bacterial cells.
Area of Science:
- Molecular Biology
- Genetic Engineering
- Bacteriology
Background:
- Plasmid F is a conjugative plasmid in bacteria, essential for horizontal gene transfer.
- Lambda phage is a bacteriophage used as a viral vector in molecular biology.
- In vitro recombination techniques allow for the precise joining of DNA fragments from different sources.
Purpose of the Study:
- To construct a hybrid plasmid capable of autonomous replication and packaging into lambda phage coats.
- To characterize the genetic and replication properties of the novel recombinant plasmid.
- To assess the efficiency of delivering the hybrid plasmid into bacterial cells using lambda phage packaging.
Main Methods:
- Construction of the hybrid plasmid using in vitro recombination of EcoRI-digested DNA fragments from plasmid F, Staphylococcus plasmid, and lambda phage DNA.
- Packaging of the hybrid plasmid into lambda phage coats using a helper phage system.
- Separation of packaged plasmid and helper phage by CsCl density gradient centrifugation.
- Transformation of F- bacterial cells with the packaged hybrid plasmid.
Main Results:
- A hybrid plasmid (2.7 x 10^7 daltons) was successfully constructed, incorporating replication functions from plasmid F, a beta-lactamase gene, and lambda phage cohesive ends (cos site).
- The hybrid plasmid demonstrated F-like replication characteristics, including copy number, incompatibility, and curing with acridine orange.
- Efficient delivery and establishment of the hybrid plasmid in F- cells were observed, though hindered by resident F factors in F+ or Hfr cells.
Conclusions:
- The engineered hybrid plasmid is a functional DNA molecule that can be packaged into lambda phage particles for delivery into bacterial hosts.
- This system offers a novel method for introducing genetic material into bacteria, leveraging the packaging and delivery capabilities of lambda phage.
- The study demonstrates the feasibility of creating artificial DNA delivery vehicles by combining elements from plasmids and bacteriophages.