Related Experiment Video
Updated: May 10, 2026
07:47
Anti-virulent Disruption of Pathogenic Biofilms using Engineered Quorum-quenching Lactonases
Published on: January 1, 2016
Novel quorum-sensing peptides mediating interspecies bacterial cell death
Sathish Kumar1, Ilana Kolodkin-Gal, Hanna Engelberg-Kulka
1Department of Microbiology and Molecular Genetics, IMRIC, the Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Mbio
|June 6, 2013
Summary
New quorum-sensing peptides from Bacillus subtilis and Pseudomonas aeruginosa trigger Escherichia coli cell death. These interspecies extracellular death factors (EDFs) enhance MazF toxin activity, suggesting potential as novel antibiotics.
Area of Science:
- Microbiology
- Bacterial communication
- Toxin-antitoxin systems
Background:
- The Escherichia coli mazEF module is a stress-induced toxin-antitoxin system mediating cell death.
- This system requires quorum-sensing (QS) signals called extracellular death factors (EDFs), such as the penta-peptide NNWNN (EcEDF), which enhance the MazF toxin's activity.
- QS molecules regulate bacterial gene expression based on population density.
Purpose of the Study:
- To investigate if QS peptides from other bacterial species can trigger E. coli mazEF-mediated cell death.
- To identify and characterize novel interspecies EDFs from Bacillus subtilis and Pseudomonas aeruginosa.
- To explore the potential of these EDFs as a new class of antibiotics.
Main Methods:
- Analysis of bacterial supernatants from B. subtilis and P. aeruginosa to identify QS peptides.
- Characterization of identified peptides as extracellular death factors (EDFs).
- Testing the effect of these novel EDFs on E. coli cultures and MazF toxin activity.
Main Results:
- QS peptides from B. subtilis (BsEDF, hexapeptide RGQQNE) and P. aeruginosa (PaEDF-1, PaEDF-2, PaEDF-3) were identified.
- These novel EDFs triggered mazEF-mediated cell death in E. coli, acting as interspecies signals.
- All identified EDFs amplified the endoribonucleolytic activity of E. coli MazF, despite sequence differences.
Conclusions:
- A new family of interspecies EDFs has been discovered, originating from B. subtilis and P. aeruginosa.
- These EDFs represent the first known QS molecules involved in interspecies bacterial cell death.
- EDFs show promise as a novel class of antibiotics that induce bacterial death extracellularly.
Related Concept Videos
01:28Gene 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,...
01:30Bacterial Signaling
Bacterial signaling can occur within bacteria (intracellular) or between bacteria (intercellular). At times, a group of bacteria behaves like a community. To achieve this, they engage in quorum sensing, the perception of higher cell density that causes changes in gene expression. Quorum sensing involves both extracellular and intracellular signaling. The signaling cascade starts with a molecule called an autoinducer (AI). Individual bacteria produce AIs that move out of the bacterial cell...
01:28Regulation of Bacterial Virulence
Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
01:30Overview of Cell Death
Cell death is an essential process where the body gets rid of old or damaged cells. Cell proliferation and death need to be balanced, as an imbalance between the two may lead to cancer or autoimmune diseases.
Cell death was observed in the early 19th century, but there was no experimental evidence to prove it. In 1842, Carl Vogt first discovered cell death in a metamorphic toad; however, it was not termed ‘cell death.’ Scientists discovered different cell death pathways only in the 20th century...
Cell death was observed in the early 19th century, but there was no experimental evidence to prove it. In 1842, Carl Vogt first discovered cell death in a metamorphic toad; however, it was not termed ‘cell death.’ Scientists discovered different cell death pathways only in the 20th century...
01:17Phagocytosis of Apoptotic Cells
Cells undergoing apoptosis form apoptotic bodies that must be removed immediately to prevent inflammation, autoimmune diseases, and necrosis. Phagocytosis is carried out by professional phagocytes such as macrophages or immature dendritic cells. Non-professional phagocytes such as epithelial cells and fibroblasts also take part in this process; however, they are not as effective as professional phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
01:12Bacterial Toxins
Bacterial toxins are sophisticated virulence factors that enable pathogenic bacteria to interact with, invade, and damage host tissues. These toxins fall broadly into two types: protein exotoxins, which are secreted into the environment and target specific host receptors, and lipopolysaccharide endotoxins, which are structural components of the bacterial outer membrane released primarily during bacterial lysis or membrane shedding. Exotoxins generally act more selectively, binding to cell...