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MIC231, a naturally occurring mobile insertion cassette from Bacillus cereus
Y Chen1, P Braathen, C Léonard
1Laboratoire de Génétique Microbienne, Université catholique de Louvain, Place Croix du Sud 2/12, B-1348 Louvain-la-Neuve, Belgium.
Molecular Microbiology
|May 13, 1999
Summary
Researchers discovered a novel mobile genetic element, MIC231, in Bacillus cereus. This element, containing a D-stereospecific endopeptidase gene, can transpose in various bacteria, suggesting a new modular organization for genetic elements.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Plasmids and transposable elements exhibit modular organization.
- The number of basic functional genetic cassettes is limited.
- A novel mobile cassette, MIC231, was identified.
Purpose of the Study:
- To describe a novel mobile insertion cassette, MIC231.
- To investigate the transposition and function of MIC231.
- To explore the prevalence and role of MIC231 in Bacillus cereus.
Main Methods:
- Identification of a novel genetic entity in Bacillus cereus isolates.
- Transposition experiments in Escherichia coli and Bacillus.
- Assay of D-stereospecific endopeptidase activity using (D-Phe)4 tetrapeptide.
- Gene inactivation studies in Bacillus cereus.
Main Results:
- A 1.9 kb mobile insertion cassette, MIC231, containing an adp gene, was identified.
- MIC231 demonstrated transposition in E. coli and Bacillus, activated by IS231 transposase.
- D-stereospecific endopeptidase activity of MIC231 was confirmed in E. coli and B. subtilis.
- The MIC231 adp gene was present in most B. cereus sensu lato strains, but its inactivation did not affect endopeptidase activity, suggesting redundancy.
Conclusions:
- MIC231 represents a novel type of mobile genetic element with a unique modular organization.
- The D-stereospecific endopeptidase activity of MIC231 is conserved across various Bacillus strains.
- The biological role of MIC231 adp remains unclear, possibly due to alternative functional genes.