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Updated: Jul 3, 2026
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Screening Foodstuffs for Class 1 Integrons and Gene Cassettes
Published on: June 19, 2015
Functional characterization of Tn1331 gene cassettes
Maria S Ramirez1, T Richard Parenteau, Daniela Centron
1Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92834-6850, USA.
The Journal of Antimicrobial Chemotherapy
|July 18, 2008
Summary
The integrase IntI1 facilitates the in vivo excision of fused gene cassettes, including aadA1-attI1*-bla(OXA-9)-attC, from the Tn1331 transposon. Even a partial attI1* site can be recognized by IntI1, enabling cassette mobility.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- The Tn1331 transposon contains a cluster of antibiotic resistance genes: aac(6')-Ib-attC-aadA1-attI1*-bla(OXA-9)-attC.
- Limited data exists on the mobility of fused cassettes and cassettes within Tn1331, which lacks an integrase gene.
Purpose of the Study:
- To investigate the in vivo mobility of gene cassettes within the Tn1331 transposon.
- To determine which cassettes are mobile in the presence of integrase IntI1.
Main Methods:
- Experiments were conducted using Escherichia coli strains harboring the plasmid pJHCMW1 containing Tn1331.
- The intI1 gene was supplied in trans, either constitutively or under the control of the P(tac) promoter.
- Plasmid DNA was analyzed using PCR and DNA sequencing to confirm cassette excision.
Main Results:
- The fused aadA1-attI1*-bla(OXA-9)-attC gene cassette was efficiently excised in the presence of IntI1.
- Excision of a DNA fragment containing aadA1-attI1* also occurred, but at a lower frequency.
- The attI1* site, a partial sequence of attI1, was recognized and utilized by IntI1, though inefficiently.
Conclusions:
- Integrase IntI1 mediates the in vivo excision of specific gene cassettes from Tn1331.
- The attI1* site demonstrates that even truncated recombination sites can function as substrates for integrases.
- These findings contribute to understanding the mobility of antibiotic resistance genes within mobile genetic elements.
