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Updated: Jul 25, 2026
08:21
Site-specific Bacterial Chromosome Engineering: ΦC31 Integrase Mediated Cassette Exchange (IMCE)
Published on: March 16, 2012
Chromosomal rearrangements in enteric bacteria
1Salmonella Genetic Stock Centre, Department of Biological Sciences, University of Calgary, Alberta, Canada. kesander@acs.ucalgary.ca
Electrophoresis
|May 20, 1998
Summary
Genomic rearrangements in Salmonella are linked to host specialization. Host-generalist Salmonella strains maintain conserved gene order, while host-specialized strains exhibit rearrangements due to recombination between ribosomal RNA operons.
Area of Science:
- Microbiology
- Genetics
- Evolutionary Biology
Background:
- Early genetic studies indicated conserved gene order in enteric bacteria.
- Genome physical mapping techniques have advanced significantly.
Purpose of the Study:
- To investigate genomic rearrangements in Salmonella species.
- To correlate genomic structure with host specialization in Salmonella.
Main Methods:
- Pulsed field gel electrophoresis (PFGE) was employed for genome physical mapping.
- Partial digestion with endonuclease I-CeuI to define the 'rrn genomic skeleton'.
- Analysis of XbaI and B1nI sites within Tn10 insertions.
Main Results:
- Conserved I-CeuI fragment order (ABCDEFG) was observed in host-generalist Salmonella species (e.g., S. typhimurium LT2) and E. coli K-12.
- Host-specialized Salmonella species (S. typhi, S. paratyphi C, S. gallinarum, S. pullorum) showed rearranged I-CeuI fragments.
- Rearrangements in specialized strains are attributed to homologous recombination between ribosomal RNA operons, causing translocations and inversions.
- Inversions not involving ribosomal RNA operons are rare, except those spanning the termination of replication (TER) region.
- Lateral gene transfer contributes to genomic "loops" with new genes, driving rapid evolution of traits.
Conclusions:
- Salmonella genome structure varies with host specialization.
- Homologous recombination at ribosomal RNA operons is a key driver of genomic rearrangements in host-specialized Salmonella.
- Lateral gene transfer facilitates adaptation and evolution of new traits in specific Salmonella strains.
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