Related Experiment Video

Updated: Jul 18, 2026

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

Siderophore-mediated cell signalling in Pseudomonas aeruginosa: divergent pathways regulate virulence factor

Paul A Beare1, Raewyn J For, Lois W Martin

  • 1Department of Biochemistry, University of Otago, PO Box 56, Dunedin, New Zealand.

Molecular Microbiology
|December 21, 2002
PubMed

Insights

Pseudomonas aeruginosa uses pyoverdine to acquire iron. A novel branched signaling pathway reveals that the antisigma factor FpvR regulates two sigma factors, controlling both virulence and iron uptake receptor FpvA production.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Bacterial Pathogenesis

Background:

  • Pseudomonas aeruginosa utilizes pyoverdine, a siderophore, for iron acquisition under iron-limiting conditions.
  • Pyoverdine-iron complexes are imported via the FpvA receptor, which also mediates a signaling cascade.
  • This cascade induces virulence factors like exotoxin A and PrpL endoprotease through the PvdS sigma factor.

Purpose of the Study:

  • To elucidate the regulation of FpvA protein production in Pseudomonas aeruginosa.
  • To investigate the role of the FpvR antisigma factor in a branched signaling pathway.
  • To identify novel mechanisms controlling bacterial virulence and iron homeostasis.

Main Methods:

  • Genetic analysis of Pseudomonas aeruginosa signaling pathways.
  • Investigating protein-protein interactions between FpvR, PvdS, and FpvI.
  • Assessing the impact of ferri-pyoverdine on sigma factor activity and gene expression.

Main Results:

  • A second signaling branch regulated by FpvR was identified, controlling FpvA synthesis.
  • FpvR negatively regulates the extracytoplasmic sigma factor FpvI, essential for FpvA production.
  • Ferri-pyoverdine binding enhances FpvI activity, inducing FpvA synthesis, demonstrating a feedback loop.

Conclusions:

  • This study describes the first known branched signaling system in bacteria regulating both virulence and receptor synthesis.
  • FpvR is identified as the first antisigma factor directly controlling two distinct extracytoplasmic sigma factors (PvdS and FpvI).
  • The findings reveal a sophisticated regulatory network for iron uptake and virulence in Pseudomonas aeruginosa.

More Related Videos

Generation of In-Frame Gene Deletion Mutants in Pseudomonas aeruginosa and Testing for Virulence Attenuation in a Simple Mouse Model of Infection08:34

Generation of In-Frame Gene Deletion Mutants in Pseudomonas aeruginosa and Testing for Virulence Attenuation in a Simple Mouse Model of Infection

Published on: January 8, 2020

Qualitative and Quantitative Analysis of Siderophore Production from Pseudomonas aeruginosa05:09

Qualitative and Quantitative Analysis of Siderophore Production from Pseudomonas aeruginosa

Published on: March 15, 2024

Related Concept Videos

Bacterial Signaling01:30

Bacterial 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...
Global Regulatory Systems01:28

Global Regulatory Systems

Global regulatory systems in bacteria enable rapid and coordinated responses to environmental changes by integrating sensory inputs with gene expression, ensuring efficient adaptation to fluctuating conditions. Key global regulatory mechanisms include regulons, two-component systems, sigma factors, and secondary messengers.Regulons and Global RegulatorsA regulon is a collection of genes and operons controlled by a common global regulator. These regulators enable bacteria to prioritize resource...
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,...
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...
Determinants of Bacterial Pathogenicity and Virulence01:20

Determinants of Bacterial Pathogenicity and Virulence

Pathogenic bacteria employ a variety of strategies to establish infections, including the secretion of extracellular enzymes that act as potent virulence factors. These enzymes facilitate bacterial colonization of host tissues and help evade immune surveillance. By targeting structural components of host tissues and interfering with immune mechanisms, these enzymes play a pivotal role in disease progression.Extracellular Enzymes Facilitating Tissue Invasion: Several bacterial pathogens secrete...
Regulation of Bacterial Virulence01:28

Regulation 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...