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Sequence of the MIR-1 beta-lactamase gene
1Edith Nourse Rogers Memorial Veterans Hospital, Bedford, Massachusetts 01730, and Lahey Clinic, Burlington, Massachusetts 01805, USA. george.a.jacoby@lahey.org
Antimicrobial Agents and Chemotherapy
|July 2, 1999
Summary
The MIR-1 beta-lactamase gene, found on a plasmid, is related to Enterobacter cloacae ampC genes. Its location suggests a potential mechanism for plasmid capture, though not a typical gene cassette.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Beta-lactamase enzymes confer bacterial resistance to beta-lactam antibiotics.
- Plasmid-mediated resistance genes are a significant public health concern.
- Enterobacter cloacae is a known source of antibiotic resistance genes.
Purpose of the Study:
- To determine the genetic relationship of the MIR-1 beta-lactamase gene to other known beta-lactamase genes.
- To investigate the genetic context and potential mechanism of acquisition of the blaMIR-1 gene on a plasmid.
Main Methods:
- Complete nucleotide sequencing of the blaMIR-1 gene.
- Comparative sequence analysis with known beta-lactamase genes, particularly ampC genes.
- Analysis of the flanking DNA regions for mobile genetic elements.
Main Results:
- The nucleotide sequence of blaMIR-1 shows a clear relationship to chromosomally located ampC genes found in Enterobacter cloacae.
- The blaMIR-1 gene is not situated within a typical integron or transposon structure (gene cassette).
- A mobile genetic element was identified adjacent to blaMIR-1, potentially facilitating its integration into a plasmid.
Conclusions:
- The MIR-1 beta-lactamase represents a plasmid-mediated variant related to Enterobacter cloacae ampC genes.
- The genetic environment of blaMIR-1 suggests a non-canonical mechanism for its capture and maintenance on plasmids.
- Understanding the genetic basis of plasmid-mediated resistance is crucial for combating antibiotic resistance spread.