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09:37
Screening Foodstuffs for Class 1 Integrons and Gene Cassettes
Published on: June 19, 2015
Inverse correlation between promoter strength and excision activity in class 1 integrons
Thomas Jové1, Sandra Da Re, François Denis
1Université de Limoges, Faculté de Médecine, EA3175, Limoges, France.
Plos Genetics
|January 13, 2010
Summary
Class 1 integrons facilitate antibiotic resistance spread in bacteria. Promoter variants influence integrase activity, impacting cassette recombination and expression, revealing a complex evolutionary dynamic.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Class 1 integrons are key genetic elements for antibiotic resistance dissemination in Gram-negative bacteria.
- They enable bacteria to acquire and express gene cassettes via site-specific recombination.
- Integrons comprise an integrase gene (intI), a recombination site (attI1), and a promoter (Pc) for cassette expression.
Purpose of the Study:
- To investigate the distribution and functional impact of class 1 integron promoter (Pc) variants.
- To correlate Pc promoter strength with integrase (IntI1) activity in recombination.
- To understand the role of Pc-IntI1 interactions in integron evolution and antibiotic resistance.
Main Methods:
- Extensive in silico analysis of class 1 integron sequences to identify Pc variants.
- Transcriptional reporter gene fusion experiments to measure Pc promoter strength.
- Assays to quantify the excision and integration activities of different IntI1 variants.
Main Results:
- Identified 13 Pc variants and 10 IntI1 variants with uneven distribution.
- Characterized five main Pc-P2 combinations with distinct promoter strengths.
- Found three main IntI1 variants with similar integration but varying excision efficiencies.
- Demonstrated a negative correlation between promoter strength and integrase excision activity.
Conclusions:
- The strength of the Pc promoter directly influences the excision efficiency of the integrase.
- A strong link exists between cassette recombination and expression capabilities of class 1 integrons.
- This relationship is crucial for understanding the rapid evolution of integrons and the complex spread of antibiotic resistance.
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