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Strategies to Investigate Membrane Damage, Nucleoid Condensation, and RNase Activity of Bacterial Toxin-Antitoxin

Stefano Maggi1, Alberto Ferrari2, Korotoum Yabre2

  • 1Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy.

Methods and Protocols
|October 26, 2021
PubMed

Insights

Studying bacterial toxin-antitoxin systems is challenging due to toxic protein expression. This research optimizes methods for studying recombinant Escherichia coli, enabling better analysis of toxin activity and cellular damage.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Bacterial toxin-antitoxin (TA) systems are crucial for microbial physiology and survival.
  • Investigating TA systems often faces challenges related to the high toxicity of expressed proteins, hindering cell transformation and stability.
  • Existing experimental methods require optimization to effectively study TA system activity and regulation in recombinant hosts.

Purpose of the Study:

  • To develop optimized methodological strategies for studying bacterial toxin-antitoxin systems in recombinant Escherichia coli.
  • To overcome challenges associated with toxic protein expression during the investigation of TA systems.
  • To enable precise monitoring of toxin activity and cellular damage induced by TA systems.

Main Methods:

  • Utilized a combination of the pET expression system and the E. coli C41(DE3) pLysS strain for tightly repressed toxin expression.
  • Developed a fluorescence-based assay using Thioflavin-T to monitor the RNase activity of the YafQ toxin.
  • Employed fluorescence microscopy with DAPI and ethidium bromide to assess membrane integrity loss caused by the Lpt toxin.
  • Applied atomic force microscopy to characterize toxin-induced membrane damage.

Main Results:

  • Successfully established conditions for tightly repressing the expression of toxic TA proteins in recombinant E. coli.
  • Demonstrated a novel fluorescence approach for quantifying the RNase activity of the YafQ toxin.
  • Visualized and quantified membrane integrity loss induced by the Lpt toxin using fluorescence microscopy.
  • Characterized specific membrane damages caused by toxins using atomic force microscopy.

Conclusions:

  • Optimized methods facilitate the study of bacterial TA systems, overcoming toxicity challenges.
  • Novel fluorescence and microscopy techniques provide sensitive tools for analyzing toxin activity and cellular effects.
  • These advancements enable deeper insights into the function and regulation of TA systems in bacterial physiology.
Keywords:
atomic force microscopyinhibition growth assaysmembrane-associated toxinsribonuclease toxinssingle-cell fluorescence microscopytoxin–antitoxin systems

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