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Updated: Aug 14, 2026

Detection of Horizontal Gene Transfer Mediated by Natural Conjugative Plasmids in E. coli
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Detection of Horizontal Gene Transfer Mediated by Natural Conjugative Plasmids in E. coli

Published on: March 24, 2023

Identification of essential genes for conjugative transfer in antimicrobial resistance-associated pELF-type linear

Jun Kurushima1, Natsuko Ota2, Yuka Yoshii1

  • 1Laboratory of Bacterial Drug Resistance, Gunma University Graduate School of Medicine, Showa-machi, Maebashi, Gunma, Japan.

Plos Pathogens
|August 12, 2026
PubMed

Insights

Linear plasmids carrying vancomycin resistance genes spread antimicrobial resistance (AMR). This study identified key genes enabling the transfer of these critical mobile genetic elements in Enterococcus faecium.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • pELF-type linear plasmids are key mobile genetic elements disseminating antimicrobial resistance (AMR) genes, particularly vancomycin resistance in Enterococcus faecium.
  • Enterococcus faecium infections are a major cause of hospital outbreaks, and understanding AMR gene spread is crucial.
  • The molecular mechanisms of conjugative transfer for these linear plasmids are not well understood.

Purpose of the Study:

  • To characterize the transfer (tra) region of the vanA-harboring linear plasmid pELF2.
  • To identify essential genes involved in the conjugative transfer of pELF-type plasmids.
  • To elucidate the molecular mechanisms of linear plasmid transmission in enterococci.

Main Methods:

  • Transcriptomic analysis to identify potential genes in the transfer region.
  • Development of a genetic manipulation framework for Enterococcus faecium.
  • Extensive mutational analysis of the transfer region and reporter assays.
  • Bioinformatic analysis of conserved genes in public databases.

Main Results:

  • Identified three essential genes for conjugative transfer: traCB4, traDD4, and traGB6.
  • Confirmed a functional promoter upstream of the identified transfer genes.
  • Demonstrated that pELF-type plasmids use a minimized conjugation machinery, similar to systems in other Gram-positive bacteria.
  • Found these genes to be highly conserved across pELF-type plasmids.

Conclusions:

  • The study provides the first molecular insights into the conjugative transfer of clinically significant pELF-type linear plasmids in enterococci.
  • Identified key genes (traCB4, traDD4, traGB6) essential for the transmission of vancomycin resistance.
  • Highlights the role of minimized conjugation systems in the dissemination of AMR by atypical mobile genetic elements.

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