Related Experiment Video

Updated: Oct 6, 2025

A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
07:10

A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues

Published on: February 19, 2019

9.1K

A qnr-plasmid allows aminoglycosides to induce SOS in Escherichia coli

Anamaria Babosan1, David Skurnik2, Anaëlle Muggeo3

  • 1Inserm UMR-S 1250 P3Cell, SFR CAP-Santé, Université de Reims-Champagne-Ardenne, Reims, France.

Elife
|January 17, 2022
PubMed

Insights

Aminoglycosides can trigger the SOS response in E. coli, leading to increased plasmid-mediated quinolone resistance (PMQR) gene expression. This occurs through nitric oxide (NO) accumulation, driven by plasmid genes ORF3 and ORF4.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Antimicrobial Resistance

Background:

  • Plasmid-mediated quinolone resistance (PMQR) genes confer bacterial resistance to fluoroquinolones, risking treatment failure.
  • Sub-inhibitory concentrations of fluoroquinolones induce the SOS response in Escherichia coli, regulating PMQR gene expression via LexA.
  • The expression of some PMQR qnr genes is controlled by the SOS master regulator, LexA.

Purpose of the Study:

  • To investigate the effect of aminoglycosides on the SOS response and qnrD gene expression in E. coli.
  • To elucidate the mechanism by which aminoglycosides induce the SOS response and NO accumulation.
  • To identify the plasmid-encoded genes responsible for NO synthesis and detoxification pathway regulation.

Main Methods:

  • Characterization of a qnrD-carrying plasmid in E. coli.
  • Assessing the induction of the SOS response by aminoglycosides.
  • Measuring nitric oxide (NO) accumulation.
  • Identifying and characterizing plasmid genes ORF3 and ORF4.
  • Investigating the roles of ORF3 and ORF4 in NO synthesis and detoxification.

Main Results:

  • Aminoglycosides induce the SOS response in E. coli, leading to elevated qnrD transcription.
  • SOS induction is caused by nitric oxide (NO) accumulation in the presence of sub-MIC aminoglycosides.
  • Plasmid genes ORF3 and ORF4 drive NO accumulation: ORF3 encodes an NO-synthesizing oxidoreductase, and ORF4 encodes a transcription factor repressing NO detoxification.
  • The Hmp-mediated NO detoxification pathway in E. coli is repressed by ORF4.

Conclusions:

  • Aminoglycosides can induce the SOS response in E. coli, contributing to the spread of plasmid-mediated quinolone resistance.
  • Plasmid-borne genes ORF3 and ORF4 play a critical role in NO synthesis and the repression of NO detoxification, mediating aminoglycoside-induced SOS response.
  • These findings highlight that antibiotic classes beyond fluoroquinolones can trigger the SOS response, with significant implications for antibiotic stewardship and resistance prevention strategies.
Keywords:
E. coliEscherichia coliSOSaminoglycosidesinfectious diseasemicrobiologyqnrstress

More Related Videos

Quantification of Plasmid-Mediated Antibiotic Resistance in an Experimental Evolution Approach12:32

Quantification of Plasmid-Mediated Antibiotic Resistance in an Experimental Evolution Approach

Published on: December 14, 2019

14.2K
Phage-mediated Delivery of Targeted sRNA Constructs to Knock Down Gene Expression in E. coli08:25

Phage-mediated Delivery of Targeted sRNA Constructs to Knock Down Gene Expression in E. coli

Published on: March 20, 2016

12.8K

Related Concept Videos

Gene Regulation in Microbial Communities: Quorum Sensing01:28

Gene Regulation in Microbial Communities: Quorum Sensing

Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
119
Stringent Response in E. coli01:23

Stringent Response in E. coli

Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
71
Antibiotic Selection00:57

Antibiotic Selection

Overview
56.1K