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Patterns of mobilization of the Proteus mirabilis chromosome by R plasmids
Abstract:
R plasmids R40a, Rip69, R447b, R769 belonging to incompatibility groups A-C, M, N, V, respectively, were investigated for chromosomal mobilizing ability in Proteus mirabilis. Plasmids R40a, Rip69 and R447b mediated polarized transfer of markers in a clockwise direction from origins near tyr-1, metF and ser-2, respectively, on the linkage map. The recovery frequency per donor cell of proximal markers approached 1 x 10(-4) for these three plasmids and the efficiency of chromosomal transfer was higher than that of the previously studied plasmid D. The plasmid-guided chromosomal trajectories overlap and it was possible to complement results obtained with plasmid D to assemble a time-of-entry chromosomal map and directly establish the circularity of the linkage group. The map comprises a length of 93 min in terms of transfer time. Plasmid R769 had a different pattern of chromosome transfer. This plasmid produced recombinants for all markers at frequencies of about 4 x 10(-6) per donor. It effected multiple and more or less simultaneous entry of markers and produced recombination over lengths of chromosome rarely corresponding to more than 10 min on the linkage map.
Insights
Four R plasmids were studied for their ability to transfer chromosomal markers in Proteus mirabilis. Three plasmids efficiently transferred markers, enabling the construction of a circular chromosomal map.
Area of Science:
- Microbiology
- Bacteriology
- Genetics
Background:
- R plasmids are known to mediate transfer of genetic material.
- Understanding the chromosomal mobilizing ability of R plasmids is crucial for bacterial genetics.
Purpose of the Study:
- To investigate the chromosomal mobilizing ability of R plasmids R40a, Rip69, R447b, and R769 in Proteus mirabilis.
- To construct a time-of-entry chromosomal map of Proteus mirabilis using plasmid-mediated marker transfer.
Main Methods:
- Investigated R plasmids (R40a, Rip69, R447b, R769) for chromosomal mobilizing ability in Proteus mirabilis.
- Analyzed polarized transfer of chromosomal markers and recovery frequencies.
- Assembled a time-of-entry chromosomal map by complementing data.
Main Results:
- Plasmids R40a, Rip69, and R447b mediated polarized chromosomal marker transfer with high efficiency (approx. 1 x 10(-4) per donor cell).
- These three plasmids facilitated the construction of a circular linkage group map of 93 minutes in transfer time.
- Plasmid R769 exhibited a different transfer pattern with lower efficiency (approx. 4 x 10(-6) per donor cell) and limited marker recombination.
Conclusions:
- R plasmids R40a, Rip69, and R447b are effective tools for bacterial chromosome mapping in Proteus mirabilis.
- The study successfully established a circular chromosomal map of Proteus mirabilis, demonstrating the utility of plasmid-mediated transfer.
- Plasmid R769's distinct transfer mechanism warrants further investigation.