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In vitro-constructed RP4-prime plasmids mediate orientated mobilization of the Proteus morganii chromosome
Abstract:
RP4-prime plasmids containing inserts of Proteus morganii strain 2815 chromosomal DNA (0.5-13 megadaltons in size) were constructed in vitro. When introduced into the latter organism, the hybrid plasmids promoted transfer of chromosomal markers in an orientated manner, with recombinant frequencies from 10(-4) to 10(-6) per donor. Transconjugants expressed the tetracycline-resistant phenotype of the plasmids. Plasmid-guided trajectories overlapped and a circular map of chromosome markers was constructed. Correspondence between size of inserted chromosomal DNA in hybrid plasmids and numbers of markers transferred suggested that homology played a role in chromosome mobilization by these plasmids.
Insights
Researchers engineered hybrid plasmids using Proteus morganii DNA to study chromosome mobilization. These plasmids efficiently transferred chromosomal markers, enabling the construction of a circular genetic map.
Area of Science:
- Molecular Biology
- Microbiology
- Genetics
Background:
- Plasmids are extrachromosomal DNA elements crucial for bacterial genetics.
- Understanding plasmid-mediated chromosome mobilization is key to bacterial gene transfer studies.
Purpose of the Study:
- To investigate the role of RP4-prime plasmids in mobilizing Proteus morganii chromosomal DNA.
- To construct a circular genetic map of Proteus morganii using plasmid-guided chromosome transfer.
Main Methods:
- In vitro construction of RP4-prime plasmids with varying sizes of Proteus morganii chromosomal DNA inserts.
- Introduction of hybrid plasmids into Proteus morganii to assess chromosomal marker transfer.
- Analysis of transconjugant phenotypes and recombinant frequencies.
Main Results:
- Hybrid plasmids facilitated orientated transfer of chromosomal markers with frequencies of 10(-4) to 10(-6) per donor.
- Transconjugants exhibited tetracycline resistance, indicating plasmid presence.
- Overlapping plasmid-guided trajectories allowed for the construction of a circular chromosome map.
Conclusions:
- RP4-prime plasmids can efficiently mobilize and transfer chromosomal DNA in Proteus morganii.
- The size of the inserted chromosomal DNA correlates with the number of markers transferred, suggesting a role for homology.
- This study provides a method for constructing bacterial chromosome maps through plasmid-mediated mobilization.