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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

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Vertical and Horizontal Transmission of ESBL Plasmid from Escherichia coli O104:H4

Sandra Daniel1, Kelly Goldlust2, Valentin Quebre3

  • 1Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198 Gif-sur-Yvette, France.

Genes
|October 21, 2020
PubMed

Insights

Multidrug resistance plasmids like pESBL spread via horizontal transfer and inheritance. This study reveals partitioning, toxin-antitoxin, and conjugational transfer systems are key to pESBL prevalence in E. coli.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Multidrug resistance (MDR) is often mediated by mobile genetic elements (MGEs), particularly conjugative plasmids.
  • The spread of MDR plasmids relies on horizontal gene transfer and stable inheritance.
  • The IncI conjugative plasmid pESBL, from a 2011 E. coli outbreak strain, is a relevant model for studying MDR plasmid prevalence.

Purpose of the Study:

  • To investigate the genetic factors contributing to the prevalence of the IncI conjugative plasmid pESBL.
  • To characterize the partitioning system of pESBL and its role in plasmid stability and spread.
  • To elucidate the interplay between partitioning, toxin-antitoxin systems, and conjugational transfer in plasmid dynamics.

Main Methods:

  • Transposon-insertion sequencing to identify the pESBL partitioning locus (par).
  • Genetic, biochemical, and microscopic analyses to characterize the partitioning system.
  • Construction and analysis of pESBL derivatives with mutations in par, oriT, and pnd genes.
  • Time-lapse microscopy in microfluidics to track plasmid dynamics.

Main Results:

  • The pESBL partitioning locus (par) was identified and characterized as a Type Ib partitioning system.
  • Inactivation of par led to mis-segregation and post-segregational killing (PSK), causing a fitness disadvantage but apparent stability.
  • A triple mutant (par, oriT, pnd) was the only derivative showing plasmid-free cells in viable populations.
  • Inactivation of the pnd toxin-antitoxin system enhanced survival of plasmid-free cells and facilitated re-acquisition.

Conclusions:

  • Active partitioning, toxin-antitoxin systems, and conjugational transfer are crucial for the prevalence of the pESBL plasmid in E. coli populations.
  • These factors collectively ensure plasmid stability, inheritance, and spread.
  • Understanding these mechanisms is vital for combating the spread of antibiotic resistance.
Keywords:
Tn-seqTnseqconjugationhorizontal gene transferparABSplasmid segregationpost-segregational killing (PSK)toxin-antitoxin (TA)

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