Related Experiment Videos
Chromosome mobilization by the R plasmid R68.45: a tool in Pseudomonas genetics
Abstract:
The conjugative plasmid R68.45 mobilizes the chromosome of Pseudomonas aeruginosa strain PAO from multiple sites located in different chromosome regions. In interrupted matings on the plate, selection for any single marker tested resulted in entry times of 3-5 min. When selection was imposed for two markers linked in R68.45-mediated conjugation, double recombinants appeared after a delay which corresponded approximately to the map distance between the two markers as measured by the sex factor FP2. Thus, R68.45 and FP2 appear to promote chromosome transfer at similar rates, but R68.45, unlike FP2, seems to give non-polarized transfer. R68.45 may be used to estimate map distances between linked markers located in those chromosome regions where other sex factors do not produce enough recombinants to permit accurate measurement of entry times. In R68.45 matings on the plate, most recombinants inherited short donor chromosome fragments (usually less than 10 min long) and lost the R plasmid during purification. Used like a "large" generalized transducing phage, R68.45 has proved valuable in construction of PAO strains with desired genotypes.
Insights
The conjugative plasmid R68.45 mobilizes the Pseudomonas aeruginosa chromosome, enabling genetic mapping. It facilitates chromosome transfer at rates similar to FP2 but offers non-polarized transfer, aiding in constructing specific bacterial strains.
Area of Science:
- Microbiology
- Bacterial Genetics
- Molecular Biology
Background:
- Conjugative plasmids are crucial for bacterial genetic exchange.
- Pseudomonas aeruginosa is an important opportunistic pathogen with a well-studied genome.
- Efficient chromosome mobilization is key for genetic manipulation.
Purpose of the Study:
- To investigate the chromosome mobilization capabilities of the conjugative plasmid R68.45 in Pseudomonas aeruginosa.
- To compare the transfer efficiency and polarity of R68.45 with other sex factors like FP2.
- To evaluate R68.45 as a tool for genetic mapping and strain construction.
Main Methods:
- Interrupted mating experiments on plates using Pseudomonas aeruginosa strain PAO.
- Selection for single and double markers to determine entry times and map distances.
- Analysis of recombinant progeny for donor chromosome fragment inheritance and plasmid retention.
Main Results:
- R68.45 mobilizes the PAO chromosome from multiple sites.
- Chromosome transfer rates are comparable to FP2, but R68.45 exhibits non-polarized transfer.
- Map distances can be estimated using R68.45 in regions with low recombinant yield.
- Recombinants typically inherit short chromosome fragments and lose the R plasmid.
Conclusions:
- R68.45 is a versatile tool for Pseudomonas aeruginosa genetic studies.
- Its non-polarized transfer and ability to mobilize from multiple sites enhance its utility for mapping and strain construction.
- R68.45 functions similarly to a generalized transducing phage for creating desired genotypes.