Tn3702, a conjugative transposon in Enterococcus faecalis

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Enterococcus faecalis is a significant opportunistic pathogen.
• Antibiotic resistance in bacteria is a growing public health concern.
• Plasmids and transposons play crucial roles in the dissemination of resistance genes.

Purpose of the Study:

• To characterize the genetic element responsible for tetracycline-minocycline resistance in E. faecalis D434.
• To investigate the mobility and integration of this resistance determinant.
• To compare the structure of the identified transposon with known mobile genetic elements.

Main Methods:

• Plasmid isolation and characterization.
• Conjugation experiments to assess transferability.
• Molecular cloning and DNA sequencing of the resistance determinant and flanking regions.
• Comparative analysis of transposon structures.

Main Results:

• A novel conjugative transposon, Tn3702, carrying the tetracycline-minocycline resistance (Tcr-Mnr) determinant was identified on the E. faecalis D434 chromosome.
• Tn3702 was shown to transpose onto both a cryptic conjugative plasmid (pIP1141) and a hemolysin plasmid (pIP964).
• Transposition resulted in an 18.5-kilobase insert in the recipient plasmids.
• The structure of Tn3702 shares similarities with the well-characterized conjugative transposon Tn916.

Conclusions:

• Tn3702 is a mobile genetic element capable of mediating the spread of tetracycline-minocycline resistance in Enterococcus faecalis.
• The ability of Tn3702 to integrate into different plasmids highlights its potential role in the dissemination of antibiotic resistance.
• Understanding the mechanisms of transposon-mediated resistance is crucial for combating bacterial infections.